United States
            Environmental Protection
Office of Research and
Washington, DC 20460
June 1997
&EPA      World of Fresh Water

            A Resource for Studying Issues
            of Freshwater Research

                   World  of Fresh  Water
                               Janet Clement1,
                       Ann Sigford2 and Robert Drummond1
                                 Nancy Novy3
                       U.S. Environmental Protection Agency
                       Office of Research and Development
            National Health and Environmental Effects Research Laboratory
                       Mid-Continent Ecology Division-Duluth
                            6201 Congdon Boulevard
                            Duluth, Minnesota 55804
1  U.S. EPA
2  Integrated Laboratory Systems (ILS)
3  Current contact: Public Information Officer (218-720-5708)

   Mention of trade names or commercial products does not constitute endorsement or
recommendation for use.

   The activities in this packet have been developed in reference to research conducted at the
U.S. Environmental Protection Agency's Mid-Continent Ecology Division in Duluth, Minnesota
(MED-D).  The research conducted at this laboratory helps us better understand the effects of
pollutants on freshwater systems (such as lakes, rivers, and streams) and determines how we can
best keep these systems healthy.

   These activities are designed primarily for students in grades 4-6, though most are adaptable
to older age groups at the discretion of the teacher.  They address a spectrum of freshwater
research efforts ranging from the methods used in collecting samples to ecosystem-level studies.
An important aspect of these activities is involvement of students and ease of use by teachers.
Each activity can be as basic or detailed as the teacher wishes.  Each can be used as  a stand-
alone activity or be presented as part of a sequence.  Materials are generally inexpensive and
easy to find.  All activities presented are intended as educational  resources for use with existing
curricula or to be used by teachers in developing new ones.

   As with all scientific experiments, you should have a specific set of SAFETY INSTRUCTIONS
for each activity. We have included "Safety Notes" to call attention to procedures where particular
care should be taken.  In general, we urge caution when you work with chemicals and glassware,
or in activities which involve student participation and movement.  When using chemicals, follow
the directions and safety procedures specified on the label by the manufacturer or specified by the
supply house. We suggest that the teacher carry out the experiment privately before presenting
it to the class.

   Our goal in developing these activities was to make them "hands-on" for students and "user
friendly" for teachers.  We  hope that you and your students enjoy and learn from the activities
contained in this packet. It is our hope that they will give students a greater understanding and
appreciation of freshwater systems as plant and animal habitat.


Notice	ii

Foreword	  iii

List of Figures	v

List of Tables 	v

Acknowledgments	  vi

Chapter 1  Water Facts and Usage	 1-1
          Taster's Choice	 1-2
          Our Tubs Runneth Over  	 1-5
          Water, Water Everywhere	 1-10

Chapter 2  Ecosystems	2-1
          Life in a Pond 	2-2
          Creating a Classroom Microcosm  	2-6
          A Wetland Ecosystem	2-8

Chapter 3  Water Pollution  	3-1
          Dilution: A Pollution Solution?  	3-2
          A Healthy Glow	3-4
          You Are What You Eat  	3-9
          Cool, Clear Water?  	3-13
          Pollution Munchers  	3-17
          Pea Soup Ponds	3-20

Chapter 4  Collecting, Sampling & Keeping Aquatic Organisms	4-1
          Aquatic Samplers 	4-2
          Active/Passive Collection Methods 	4-6
          Making a Classroom Aquarium  	4-9
          Raising Algae and Water Fleas	4-11

References	 Ref-1

Appendix A Glossary of Terms  	A-1

Appendix B Additional Resources	B-1


1-1.       Data sheet; taster's choice results	  1-4
1-2.       Data sheet; student water use	  1-8
1-3.       Water use cards 	  1-9
2-1.       Wetlands food web  	2-10
3-1.       Data sheet; effects of a pollutant on Daphnia  	3-8
3-2.       Zooplankton cut-outs	3-12
3-3       Student comment sheet; cool, clear water	3-15
3-4.       Algae growth chart  	3-23
4-1.       Equipment construction for water samples  	4-5
4-2.       Schematic of aquarium construction	4-10

1-1.       Water use by average American	  1-6
1-2.       Water use by country	  1-7
1-3.       World's water supply relative to 1-liter total	  1-11
3-1.       Water pollution and its effects on fish  	3-16


   The authors wish to acknowledge contributions of a number of people to this manuscript.
Names are listed by categories relative to the roles of their contributions and alphabetized for
ease of reference.

Janet Clement
Robert Drummond
Ann Sigford, Integrated Laboratory Systems


Richard Anderson
John Brazner
Dave Janssen, University of Minnesota-Duluth
Jamie Juenemann, Integrated Laboratory Systems
Barb Liukkonen, Minnesota Extension Service
J. Howard McCormick
Gary Phipps
Technical Reviewers

Allan Batterman
Steve Bradbury
John Brazner
Marna Butler-Fasteland, Integrated Laboratory Systems
Elizabeth Durhan
Philip Monson, Integrated Laboratory Systems
Editorial and Production Support

Evelyn Hunt
Nancy Novy
Judy Vee, Integrated Laboratory Systems
Roger LePage, Computer Data Systems Inc.

                                     Chapter 1
                              Water Facts and Usage
       Earth has been called the "water planet" with good reason; water covers 75% of the globe.
However, water does not restrict itself to the surface of the planet.  It also filters through the crust
of the Earth and floats in the atmosphere, in vapor form, as clouds.  Earth is the only planet in our
solar system with water on the surface, underground, and in the atmosphere.

       Water obeys the laws of gravity. It seeks the lowest level  possible, finding its way into any
space into which it is able to flow. Through its constant wanderings, water is one of the major
forces that shapes our planet.

       It was the arrival of water on our planet that allowed life to develop. Without water, there
would be no life,  and water quality has a great influence on the quality of life.

       Water appears to occur in such abundance that it  seems we have an unlimited  supply
available for human use. However, the amount of available fresh water is comparatively tiny; only
about   of 1% of the world's water.  This activity will help students understand that only small
amounts of water are available, and it will show them  how much we depend on fresh water in our
daily lives.
                                         1 -1

                                  Taster's Choice

       Overview:  Students sample various waters to select the best for drinking.

       Objective:  To understand the importance of quality, fresh water in our lives.

       Materials for 28 Students:  77 small paper cups; 5 clean, empty 2-liter pop bottles
       plus a 2-liter bottle of carbonated water; tap water; 1 Tbsp. each salt, sugar, and lemon
       juice; 1 tsp. alum;  7 data sheets.

       Teaching time:  30-45 minutes.

NOTE: This activity is planned for 28 students working in 7 groups of 4.  It may be easily modified
for more or fewer students.

Teacher Instructions

A.     Before the lesson:

1.     Obtain supplies.  Alum is usually available from  the  spice section of grocery stores.
       Remove the  label from the carbonated water bottle.

2.     Label the 2-liter bottles 1 through 6, with (1) being the carbonated water. Make up the
       other 5 2-liter water samples as follows; (2) plain tap water, (3) tap water plus 1 tablespoon
       salt, (4) tap water plus 1 tablespoon sugar, (5) tap water plus 1 tablespoon lemon juice,
       and (6) tap water plus 1 teaspoon of alum.

3.     Label 42 small paper cups with numbers 1-6. There will be 7 number Ts, 7 number 2's,
       etc. Students may do this as part of the activity if you wish.

4.     Each of the 7 stations will require:  a set of 6 cups labeled 1-6; 4 drinking cups; 1 "spit"
       cup; 1  Taster's Choice data sheet; pencil.

B.     With the students:

1.     Break into 7 groups of 4 students.  Introduce the activity as an investigation into the
       importance of "clean" water for drinking. Explain that none of the samples are dangerous
       to swallow, although some will certainly taste better than others.

       Safety note: Warn students that tasting is not a good way to find out whether water is safe
       for drinking.  In this activity, the flavored waters provided are safe to taste.

       Students who do not wish to swallow their samples can use the "spit" cup. It is important
       that the tasting cups be emptied before the  next round begins so each round starts with

                                         1 -2

       an unmixed water sample.
2.      Six students can distribute the appropriate water samples to the numbered cups at each
       station. Each student will use his/her paper cup to taste each of the 6 samples.  After each
       taste, a student recorder should write down the reactions to the sample on the student
       observation sheet provided. You may choose to begin with the group tasting one water
       at a time to make sure students do not taste too fast for the recorder.

3.      Summarize results on the board, in chart form, with student recorders supplying group
       opinions.  Discuss with the class the results of their observations. Ask the students to
       choose which one of the six water samples would they prefer to be coming out of their taps
       at home and in school. Students usually prefer the plain tap water.

4.      Tell the students that the tap water they use every day is an example of fresh water.  Ask
       them to come  up with a definition of fresh water and write that definition down on their
       observation sheets. A typical definition would be that fresh water is not salty.

5.      Using the board, brainstorm how people use water.  Let the students pick one of these to
       make a poster of themselves, their families, or their friends using water in one of the ways.
       They may wish to use their definition of fresh water as a starting point for a slogan.

7.      Clean up:  Liquids can be safely poured down the sink.
                                         1 -3

My definition of fresh water is:
Remember:  do not taste unknown water samples except these provided by the teacher!
Figure 1-1.  Data sheet, taster's choice results.
                                     1 -4

                             Our Tubs Runneth Over
                      (Adapted from Environment on File, 1991)

       Overview:   Students  estimate their personal water use  and compare  this  to U.S.
       averages, as well as compare U.S. water use to other countries.

       Objective: To examine the use of fresh water in the U.S.

       Materials For 28 Students:  Student worksheet (Figure 1-2); 7 sets of paper water-
       use cards (Figure 1-3); 7 1-cup measures; 6 large containers, such as garbage cans; water

       Teaching Time: Approximately 45-50 minutes.

Note:  This activity is planned for 28 students working in 7 groups of 4.  It may be cut down or
expanded as needed.

Teacher Instructions

A.     Before the lesson:

1.      Make 7 copies of the water use cards sheet, and cut them to make 7 sets of "cards."

B.     With the students:

1.      Organize groups of 4 students. Brainstorm the many ways we use fresh water. See if
       students can figure out the 6 main ways we use water at home (see next page). Give each
       group  cards listing each of the 6 different categories.  Their job is to place the cards on
       their desk or table in order of the largest amount to smallest amount of water used by their

2.      On the group's worksheet, have them estimate how many cups of water in each category
       they use each day.

3.      According to Environment on File, each person in the U.S. uses an  average of 6,320 liters
       of water every day. If you would like the students to convert this to cups, multiply by 4.23
       cups per liter (26,734 cups). The next highest water user is Canada where usage is 4,130
       liters of water per person, per day.  These figures include water used in industry and
       agriculture.  It is added on to the personal totals because, as citizens of the United States,
       we all benefit from the use of water by these industries. However,  only about 12% of this
       per-person total is used by individuals at home. Multiplying 6,320 liters by 12% gives us
       a daily per-person water use of 758 liters per day at home or about 3,206 cups per person,
       per day.
                                        1 -5

4.      Knowing this, and estimates for the percent of water use by different categories, we can
       figure out about how many cups of water the average American uses for each of these
       activities each day (Table 1-1).  Ask the students to compare the values that they predicted
       in their groups to professional estimates for each of the water uses.  Most people greatly
       underestimate their water use.
Table 1-1. Water use by average American.

 Water Use                             Cups                   Percent of Total Use

 Washing/showering                    865                            27

 Toilet flushing                          769                            24

 Running washing machine              545                            17

 Doing dishes                          449                            14

 Cooking/drinking                       321                            10

 Gardening/washing cars                256                            8
5.      To give the students an idea of how much water this actually is, groups can fill garbage
       cans for each category by counting cups of water into them.  The 769 cups of water for
       toilet flushing will nearly fill a 50-gallon garbage can. If you have a non-slippery outdoor
       area, you may choose to fill the cans by setting up a relay race.

6.      Water use varies a great deal by country (Table 1-2). Ask the students to guess the top
       10 countries for water usage, and rank them on their worksheet with the highest on top.
        Discuss the reasons why the United States uses so much  water compared to other
       nations  (habits, irrigated  agriculture,  technology to withdraw and deliver water, and
                                         1 -6

Table 1-2. Water use by country.
United States
New Zealand
United Kingdom
Amount of Water
Used Daily (liters)
7.     You may want the students to find these countries on the map and write in how many liters
       of water each person uses per day in each country.  Does this give some clues as to what
       types of countries are the big water users?
                                          1 -7


How many cups of water/day do you use while:

      1.   Washing/showering            _

      2.   Toilet flushing                 _

      3.   Running washing machine      _

      4.   Doing dishes                  _

      5.   Cooking/drinking              _

      6.   Gardening/washing cars       _
Usage of Water by Country (greatest usage on top)

      RANK            ESTIMATE                 ACTUAL










Figure 1-2. Data sheet, student water use.
                                         1 -8

Figure 1-3. Water use cards.
                                                     1 -9

                            Water, Water, Everywhere?
                    (Adapted from Project Stewardship Minnesota)

       Overview:  Students see what proportion of the world's water is fresh water.

       Objective:  To demonstrate the relatively small amount of fresh water available for our

       Materials for Demonstration:  9 clear, 1,000-ml containers such as mayonnaise jars;
       labeling pen; masking tape; graduated cylinder (if available); tablespoon; medicine dropper
       or pipet; water supply.

       Teaching Time:  15-25 minutes.

Note:  This activity is described here as a demonstration, but it can be adapted to be done by

Teacher Instructions

A.     Before the lesson:

1.     Label 8 jars with masking tape and pen:  Ocean, Icecaps/glaciers, Groundwater, Saline
       lakes, Freshwater lakes, Soil moisture, Atmosphere,  Rivers.  Label one jar on one side "All
       the Water in the World" and on the other side, "Currently Useable Fresh Water."

B.     With the students:

1.     Remind the students of their definition of fresh water, if they have done the Taster's Choice
       activity, or  use a working definition that fresh water is water that is not salty.

2.     Show the class the "All the Water in the World" jar, and ask them to pretend that all of the
       Earth's water will fit into this jar. Fill it with 1,000 ml water.

3.     Using the World's Water Supply (Table 1-3),  measure out the following amounts and pour
       into the appropriate container:
                                        1 -10

Table 1-3. World's water supply relative to 1-liter total.
Amount (ml)
 Percent of Total
 Groundwater (down to
 Saline lakes
 Freshwater lakes
 Soil moisture
973 or 4 cups
21 or 1.5 tablespoons
6.1 or .5 tablespoon

0.08 or 2 drops
0.09 or 2 drops
0.05 or 1 drop
0.01  or 1/5 drop
not enough to be measured
97 (approximately)

       At this point, the original jar should be empty.
       Ask the students to offer ideas about which of these are currently available as inexpensive
       sources of useable fresh water.
       Turn the original jar around to show the "Currently Useable Fresh water" side. Add back
       the amounts of water that are currently useable by industry, including agriculture:
               of the groundwater (the other  is too salty),
             nearly all of the freshwater lakes,
             nearly all of the soil moisture,
             nearly all of the river water.
       Ask the students how much of this industrially useable water they think would be fit for
       drinking as it is. There are no accurate figures for this, but it could be about half.
       Discuss with the class all  of the uses that we have for water, and then compare it to the
       relatively small amount of fresh water that we actually have available.
                                         1 -11

                                     Chapter 2
       Our environment contains natural associations called "ecosystems." Examples include
ponds, bogs, and forests. Some may be very small, like the ecosystem in a fallen log. Some may
be very large, like Lake Superior. In this section, we will look at ponds, wetlands, and miniature
freshwater ecosystems.

       Each ecosystem  has its own source(s) of energy, nonliving components, and living
components. The source of energy is usually the sun.  Nonliving components include air, water,
and minerals.  Living components include plants, animals, bacteria, and fungi. A proper balance
of these components allows the system to stay healthy.

       In addition to understanding how ecosystems depend on a proper balance of components,
we need to begin to understand the role of humans within the ecosystem.  People are a part of
many aquatic ecosystems, and what we choose to do as part of our everyday lives affects these
ecosystems. Too often we view ourselves as outsiders to natural ecosystems when nothing could
be further from the truth. We need to include ourselves so we recognize our connection to, and
reliance on, ecosystems as well as our potential for altering them.

       This section includes lessons that help students understand the importance of  balanced
interactions in ecosystems and the importance of each part.

                                   Life in a Pond

       Overview:  Students play an active outdoor game, taking the roles of Daphnia and
       dragonfly nymphs, which are two members of the pond ecosystem.

       Objective:  To simulate food-chain interactions through student play.

       Materials for 1 Classroom: "Members of the Pond" information sheet; several small
       boxes; either 1  large bag each of white and colored popcorn or slips of paper; materials
       to make name tags for predator/prey; cones or string; whistle.

       Teaching Time:  45-eo minutes.

Note: This activity is planned for an entire classroom to play.

Teacher Instructions

A.     Background information:

       A food chain is an interaction of plants and animals in their quest for survival. A food chain
starts with a plant that is able to use energy from the sun, and nutrients from its surroundings, to
make food.  Small organisms can eat the plant for food.  In turn, the small  organisms become food
for larger animals. They may then become  food for even larger animals and so on up the food
chain.  The animals that are eaten in a food chain are called prey; the animals that eat other
animals for food are called predators.  A food chain  can be as simple as three organisms or very
complex with many different predator/prey interactions.  When an organism in the food chain dies,
it becomes nutrients for the plants at the base of the food chain.  In most healthy food chains,
there is a mix of different organisms on each level of the food chain - many organisms at the base
of the  food chain and fewer at  the top.  The following  game is designed to help students
understand this relationship as it occurs in a freshwater pond.

B.     Before the lesson:

1.      Select and inspect a playing area.  It should be a large open area such as a gym or a field.
       Mark off a large portion of this area as the "pond" using cones or string.

2.      Decide what you want to use for "green algae" and "blue-green algae." One choice is
       white popped corn for "green algae" and colored popped corn for "blue-green algae" or
       slips of paper saying "algae" and "blue-green algae."  An advantage of the popcorn is that
       students can eat it as long as proper hygiene is observed.

C.     With the students:

1.      Using the background information provided, review food chains, and explain that students
       will have a chance to be predators or prey. Use the "Members of the Pond" information
       (p. 2-5) to introduce the organisms and learn their roles.

2.      Show the students the popcorn or slips of paper representing green and blue-green algae,
       and emphasize that the blue-green algae is not a good food source for Daphnia compared
       with green algae. Signify one-third of the class as  dragonfly nymphs (the predators) and
       two thirds  of the class as Daphnia (the prey).  Each student should make a  name tag
       telling what organism they are. Cover the rules  of the game as listed below.

3.      To play the game:

       a.     Place several boxes of mixed green and blue-green "algae" around the playing

       b.     The game begins with dragonfly nymphs on one side of the playing field and the
             Daphnia  on the opposite side of the  field.  The object  of the game  is for the
             Daphnia  to reach  the  opposite side  of the pond without being "eaten" by a

       c.     Daphnia  "eat" by taking one kernel of popcorn or one slip of paper.  Dragonfly
             nymphs "eat" by tagging Daphnia.

       d.     To  move across the field, the predators  and  prey must follow some "laws of
             nature."  They can move only when the  whistle blows to  start a round, and they
             must move only a  certain number of steps  each time.  The end of a round will be
             marked with two blasts from the whistle. When they die or are eaten, they must
             move to the edge of the pond until a new generation is born.

       e.     When the whistle is blown, each Daphnia can take ten large steps. If they reach
             food, they will take one kernel of popcorn (or one slip of paper). If they eat a green
             alga, on their next turn they will be allowed ten more steps.  If they eat a blue-green
             alga, they will be allowed only five steps. If they reach no food, they are allowed
             two steps.

       f.      Meanwhile,  when the whistle is blown, the dragonflies are also allowed ten steps.
             If they eat a Daphnia (by tagging the person), they will be able to move ten steps
             in the next round. If they reach no food, they will still be able to move ten steps in
             the next round because larger organisms can go a longer time without food.

       g.When everyone understands the rules, start the  game with a whistle. After everyone has
       moved and eaten (or not eaten), blow the whistle twice to stop the action. Any organism,
       which does not find food two rounds in a row, will sit  out for one round if a Daphnia and two
       rounds if a dragonfly nymph (Daphnia have a shorter regeneration time than  dragonfly
       nymphs). After that, they will return to the side where they began and start again when the
       whistle is blown for the next round.

       h.     Continue for a third and fourth round.  When a Daphnia makes it across, the game
             can be concluded, or the Daphnia can immediately return to the other side of the

             Safety note:  The students have to be careful when "tagging."  If the students eat
             the popcorn, they need to be careful while eating to avoid choking.

4.      After the game, discuss the interactions between predator and prey, and discuss the
       results of the game in relation to pond food chains.  Typical observations:

                   It is easier for dragonflies to eat when there are a lot of Daphnia but difficult
                    when they get scarce.
                   When the green algae are gone, the Daphnia are in more danger.
                   If some  dragonflies "starve", the  Daphnia can "catch up" somewhat in

5.      Clean up: All slips of paper should be removed from the playing area. Small amounts of
       popcorn that remain in an outdoor play area will be eaten by birds.

                               Members of the Pond
       Many living things in  pond water are plankton (tiny plants or animals), while other
organisms are larger, such as insects. In this exercise, we will look at three kinds of plankton and
one example of an insect.

Green Algae

       These phytoplankton (plant plankton) take nutrients from water and energy from sunlight
to make sugar.  This is valuable food for small animals. Algae are the base of our pond's food
chain  and also add  oxygen  to the  water.  Although they are often called plants, most
phytoplankton are really protists.

Blue-green Algae

       Blue-green algae (also known as cyanobacteria) also take nutrients from the water and turn
it into sugar.  But for some reason,  blue-green algae don't "taste" as good as the other types of
algae  to most  small animals and  are not a  preferred food.  Blue-green  algae can also be
dangerous to the life of a pond. If too many nutrients get into the water (usually through some sort
of pollution), the blue-green algae divide very quickly and then float to the top, forming "blooms."
Blooms prevent sunlight from getting  to the bottom of the  pond which makes it hard for the green
algae, or other plants, to survive. When they die, they rot,  which uses up the oxygen that is in the
water.  If the bloom takes over the entire pond or lake, the other organisms  in the water have a
hard time surviving and will probably die. Ponds and lakes in which this occurs smell terrible.


       These water fleas are one type of zooplankton or animal plankton. They are one of several
different types of tiny animals that eat algae and serve  as food for larger animals. They much
prefer  green algae to blue-green algae. Daphnia can  be found in our pond  in large numbers
because they are  near the base of the food chain.

Dragonfly Nymph

       A dragonfly nymph is a young dragonfly. It is not a larva because it does not go through
complete metamorphosis  like a butterfly does. Instead, the dragonfly nymph looks a lot like an
adult dragonfly without the wings. In our pond, it is  a predator of Daphnia.  There are also animals
that will feed on the dragonfly nymph (such  as  the bluegill sunfish) but, for this exercise, the
dragonfly will have no predators.

                         Creating a Classroom Microcosm

       Overview:  Students start and maintain mini ponds (microcosms) in a jar.

       Objective: To grow several different microcosms from different ponds or from different
       areas of the same pond.

       Materials for 28 Students:  7 quart-sized glass or clear plastic jars (such as canning
       jars); 7 plastic or metal buckets; hand lenses; microscopes if possible; pond site(s).

       Teaching Time: 30-50 minutes of one class period then a few minutes of several class
       periods thereafter.

Note:  This activity is planned for 28 students working in 7 groups of 4. It may be easily modified
for more or fewer students.

Teacher Instructions

A.     Background information:

       There are a variety of plants, animals,  and nutrients in every living system.  Plants use
nutrients, and energy from the sun, to make food that animals can use. When plants and animals
die, or when animals eliminate wastes,  nutrients are released that plants can use again as food.
Usually these systems are complex and  have many members.  You can observe a relatively
simple system by  making a microcosm (tiny world). A microcosm is an interacting system of small
organisms  in an enclosed space.  Microcosms are  used  by scientists who need contained
ecosystems in which to test the effects of chemicals or introduced species.  In this lesson,
students will make microcosms to observe in the classroom.

B.     Before the lesson:

1.      You must first find a pond from which students can safely collect samples. Dried ponds
       work well because they contain eggs of many small organisms that "hibernated" when the
       pond went dry. Add pond water or aged tap water to the mud to  allow the eggs to hatch.
       If you only have wet ponds to choose from, you will need to devise a way to get a sample
       of the pond bottom.  Choices include wading with shoes or boots, using a shovel or rake,
       or making the bottom scraper from the "Aquatic Samplers" activity in this guide.

C.     With the students:

1.      Review the concept of an ecosystem,  using the background information provided, and
       explain that each group of 4 students will be able to make a small aquatic ecosystem in
       a jar- a microcosm.  They will use plastic buckets for collecting and carrying mud from the
       pond and  then transfer mud and pond water to their microcosm.

2.     At the pond site, each group should collect about  1 cup of mud and 1 liter of water.
      Instruct each group of students to collect their samples from different areas of the pond
      and at different depths, if possible. Each group should record the location from which their
      sample was taken.

      Safety note: Pond sampling should always be done with an eye to safety.  The greatest
      hazard is often litter such as glass on the bottom.  For that reason, make sure the students
      wear shoes. The completed microcosms are  somewhat heavy  and may be slippery.
      Students should fill the microcosms where they will stay so they do not need to carry them
      around  the classroom.

3.     In the classroom, groups should add 1-2" of mud to the microcosm jars, then add pond
      water to near the top. Cover the jars loosely with plastic or lids. Punch holes in the top so
      that air can get in and out of the jar.  Store the jars in a lit area - but not in direct sunlight.
      Direct sunlight will cause the microcosm to heat up, and the organisms inside will die.

4.     Observe the microcosms daily  with hand lenses,  and have the students record their
      observations.   Samples  of  the microcosms  can  be removed  and examined under
      microscopes.  Talk about differences in  the types of organisms  present (such as one
      sample with no visible  organisms versus others  with many)  or differences in the
      appearance of the jars (such as greenish versus clear water) between the different sites.
      This information can be graphed by site. For example, make a bar  graph with the vertical
      axis the number of organisms and each bar referring to a different microcosm.  You may
      want to talk about food chains after observing the microcosms for a period  of time.

5.     Clean up: The microcosms should be returned to the pond from which they came. This
      can be part of the activity.  If they  came from a dried pond, they can be returned to similar
      shallow ponds in the area.

                              A Wetland Ecosystem

       Overview:  Students take on roles of wetland organisms and create a web with string
       that connects them.

       Objective: To demonstrate the importance of all parts of an ecosystem using a wetland
       as a model.

       Materials  for  28  Students:    Photos,  drawings,  or name  signs  of  specimens
       representing different members of a wetland ecosystem; a large ball of yarn or string.

       Teaching Time: 45-50 minutes.

Teacher Instructions

A.     Background information:

       Wetlands are areas where water and land meet, forming a boundary between water
ecosystems and land ecosystems. Wetlands have a diversity of plants and animals all their own.
In recent years, much attention has been given to the preservation of wetlands because many of
them are being destroyed to make way for human habitation or other developments.  There are
many different types of wetlands, but this lesson uses a "generic" simplified cast of organisms that
could be found in wetlands anywhere in the United States. For more information, see the book
Wetlands listed in the Appendix B.

B.     Before the lesson:

1.     Decide how to represent the members of a wetland ecosystem.  Photos work well,  but you
       can also make drawings or name signs to depict each of the organisms.

C.     With the students:

1.     Begin the lesson by defining wetlands using the background information provided.

2.     Go over the "Parts of the Wetland" included with this activity. This is a partial list of living
       and nonliving components that might be found in a wetland.  As you go through the list,
       hold up the representation (photos, drawings, or name signs) of each of the components.
3.      Have the students sit in a circle with the representative wetland components in the middle.
       Tell the students that they will become the wetland by choosing to be different parts of the
       wetland. Include a sample of water and a representation of the sun in the collection.

4.      Allow each student to choose to be one part of the wetland.

5.     After all students have made their choices, take a look at your wetland.  The students most
      often choose the organisms that they are most familiar with or those that seem to them to
      be the most important (the bigger ones). Ask for a show of hands as to who chose what,
      starting with water.  If no one chose water, then you have no wetland, and you need to
      place  all of the components back into the center and choose again - everyone must
      choose a different part of the wetland.

6.     Once you have water, ask again for a show of hands as to who chose which component.
      Start again with water.   Emphasize how important water is to everything else in the
      wetland. Next, ask for those who chose to be algae or other aquatic plants.  If no one (or
      very few) chose plants, you need to start over again because plants are the base of the
      food chain and without  plants, the animals could not use the energy from the sun to make
      food (as the plants can), and you have no wetland.

7.     Repeat this exercise until you get a variety of water, plants, and animals.  Discuss the
      importance of having  a variety  of plants and animals within the ecosystem.  Ask the
      students which part of  the ecosystem was the most important - the large, visible animals
      and plants or those that we rarely think of as being  animals and plants. Or are they aN

8.     Using  a large ball of yarn, start with water and sunlight  and ask what members of the
      wetland use these things. Connect students with yarn as they demonstrate relationships.
      Cut the yarn  whenever it becomes cumbersome.  Eventually it should be clear that all
      members of the ecosystem are connected.  Try tugging on  one link of the web and seeing
      how many students can feel it. If each student who feels the tug pulls on the lines he or
      she is holding,  the original tug will ripple through the whole community just as wetland
      disturbances  affect many organisms.

Parts of the Wetland



Water: 5 to 7 small jars.
               Plant Eaters:
                              2 to 4 rooted plants (cattails or bulrushes).
                              5 to 7 samples of algae.
                              2 to 3 zooplankton (microscopic animals)
                              2 to 3 turtles
                              2 to 3 ducks
                              2 to 3 frogs
               Medium-sized Animals:
                             1 to 2 snakes
                             1 to 2 snapping turtles
                             1 to 2 fish
       6.      Predator: Mink

Figure 2-1. Wetlands food web.
                                      Wetland Food Web
                      Humans     Wading Bird       Diving Birds      Mmk   Otter
                               (herons/egrets)   (loons/terns/grebes).
               Zooplankton Insects/Bugs'Crayfish Salamanders Frogs Turtles Ducks Muskrats Beavers
                          Rooted Plants     Duckweed     Algae      Trees

                                     Chapter 3
                                  Water Pollution
       In the past,  scientists were concerned about visible forms of water pollution.  Large
quantities of raw sewage and hazardous wastes were dumped into our fresh water.  Increased
amounts of pollution in the water caused the water to become discolored and smelly and changed
the water until some of it was dangerous to life. In extreme cases, fish died in large numbers.

       These obvious signs created much concern for environmentalists.  Research studies
showed the effects of pollution not only on fish, but also on various species throughout the food
chain.  In 1964, Rachel Carson reported much of this in a book called Silent Spring.  This book
attracted much public attention and pointed out the magnitude of the problem.  People realized
the need for action and figured out what needed to be done. Agencies were formed,  rules were
written and enforced, and water quality improved.

       However, water pollution problems did not disappear.  The water pollution problems we
have today are terribly complex and difficult to study. These days, most water pollution is invisible.
In addition to oil spills and toxic leaks, we must deal with less obvious pollutants.  Thousands of
chemicals are present in the water and sediments -  some are toxic, some build  up in  the food
chain and become  toxic, and some are toxic only when  combined with other chemicals. Many are
present in  such small amounts  that they are  hard to  measure.   Scientists  must  conduct
experiments to test the nature of each potentially harmful chemical so standards can be set. This
task is both time consuming and costly, but failure to address water pollution problems could result
in disaster because the health of our planet, and  all of us that live here,  depends on the quality
of our water.  In this section,  the lessons address the complexities of  today's water  pollution

                           Dilution:  A Pollution Solution?

       Overview: This quick demonstration involves diluting a beaker of colored water with
       clear water.

       Objective: To show that dilution takes a very long time and may not be a good solution
       to a water pollution problem.

       Materials for Demonstration:  1 empty aquarium or other large clear container; 2
       500-ml beakers or mayonnaise jars; tap water; red food color.

       Teaching Time: 40 minutes.

Teacher Instructions

A.     Background information:

       Lakes have many  sources of "new" water, including  runoff from surrounding land,
groundwater, and  rainfall on the surface of the lake. This "new" water gradually replaces the
existing lake water, which may evaporate or be discharged through an outlet. The amount of time
for enough "new" water to replace all the lake's water is called  retention time.  It is also called
renewal time or even flush rate. It is a useful concept because it gives an idea of how often the
lake water is "renewed." The amount of time varies greatly - from 9 years for Lake Erie, to nearly
200 years for Lake Superior.

       Sometimes people think of this as how much time would be needed to "flush" the lake of
pollutants.  There are two important considerations here:  where does the polluted water go (does
it go to pollute a  river,  or another lake?) and whether one  renewal time would actually flush the
lake clean. This  exercise addresses both of these concerns.

B.     With the students:

1.      Fill one of the beakers  or jars with tap water, and stir in a few drops of food color so that
       it is bright red.  Explain to the students that the red food color could represent a pollutant
       that is in a nearby lake.  It is nice to think that clean rainwater could eventually dilute the
       pollutant so the  lake would be clean again. Ask the students how long they think this might
       take (answers will vary).

2.      Try one complete renewal of water. To do this, fill the second beaker with tap water.  This
       will represent the amount of rain and other new water that would completely replace the
       existing lake water.  Have a student hold the "polluted" beaker over the aquarium, while
       you gradually pour clean tap  water into the "polluted" beaker.  The waters will  mix and
       overflow into the aquarium, and it will be  evident that much of the "pollutant" is gone from
       the lake.

3.      Ask if the red color can still be seen in the lake. If it can, you have demonstrated that more
       than one retention time is  needed to flush pollutants from your imaginary lake.  Try a
       second complete renewal, again pouring the new water on top of the lake.  It will typically
       take 3 or 4 replacements before you can no longer see the "pollutant."  Ask the students
       if they  feel sure the pollutant is completely gone once they can no longer see it.  Actually,
       our eyes are rather unreliable at detecting pollution - small amounts of pollutants tend to
       be invisible to us.

4.      Introduce  the concept of retention time and that it varies from lake  to  lake.  Typical
       retention times for medium-sized lakes in the Midwest is on the order of 3-10 years. Lake
       Superior takes much longer. Calculate the number of generations it would take for Lake
       Superior to renew twice (200 x 2 divided by 25  = 16 generations). That is why we must
       protect our lakes now to prevent pollution that will be with us for so long.

5.      Now examine the water that overflowed from the  "polluted" lake.  Did the pollutant go
       "away"?  Discuss what away means. It is a key problem in pollution control that we often
       simply move pollutants around rather than  solve the problem.

6.      Another aspect of the dilution "solution" is to consider the source of renewal water.  If this
       water  is polluted, the lake may never be clean again.

                                   A Healthy Glow

       Overview:  Students perform an  experiment dealing with the effect of a pollutant
       (vinegar) on a small aquatic organism called Daphnia magna.

       Objective: To see how a pollutant can affect the eating activities of a living organism.

       Materials for 28 Students:  210 Daphnia: 1 gram sugar-dye compound (4-methyl-
       umbelliferyl-beta-d-galactoside); 3 ml vinegar; lake water or aged tap water; ultraviolet (UV)
       light source (a black light works best); viewing box for black light; 42 30-ml beakers or baby
       food jars; 7 droppers or pipets with  wide openings; graduated cylinders (100 ml, 50 ml, 5
       ml); a 1-liter bottle.

       If students prepare their own dilution series, you will need 21 graduated cylinders (7 each
       100 ml, 50  ml, 5 ml). If you prepare the solutions for students, you will need 1  of each size
       graduated  cylinder.

       Teaching Time: Approximately two 50-minute class periods.

Note: This activity  is planned for 28 students working in 7 groups of 4.  It may be easily modified
for more or fewer students.  It may also be a demonstration.

Teacher Instructions

A.     Background information:

       A toxicity test is one type of experiment used by scientists studying water  pollution.  A
toxicity test makes use of live organisms to assess safe and unsafe levels of toxic chemicals in
the water. The purpose  of the experiment is to determine what amount of the pollutant in the
water will harm an organism and in what way.  This is an important issue for researchers who must
give information to those who write regulations that affect business and industry.

       The organism we will use is the water flea Daphnia magna. They are near the base of the
food chain, eating small plants for food and being eaten by larger animals. The health of this little
animal can determine the health of the entire food chain.  Different types of water fleas are often
used in these types of experiments because they are found nearly everywhere, can be raised
easily and consistently in  a lab  (or a classroom), and are sensitive to many pollutants.

       This experiment will show how a pollutant may affect an organism.  Effects of pollutants
are often subtle. For example, a chemical  may not kill an organism, but might deform it in some
way, slow it down so it can't catch food or can't escape a predator, interfere with its ability to
reproduce, or be passed on to  its offspring.  In this experiment, we will be looking for non-lethal
effects, particularly, loss of the  desire or ability to eat.

       The pollutant we will use is vinegar, which is a weak acid. This is a very relevant choice
to make since acid precipitation is a very real environmental problem. Straight vinegar is 5%
acetic acid which would kill any Daphnia we put into it.  We do not want to kill any Daphnia. but
see how vinegar affects their eating habits and health.

       In order to see which Daphnia are eating and which are not, we will feed them a "sugar-
dye." In this compound, the sugar and the dye are connected in such a way that we cannot see
the dye. But if this connection is broken, the dye glows when viewed under ultraviolet light. When
the Daphnia eat the sugar-dye, they break the connection between the sugar and the dye.  This
makes  the dye visible in the transparent bodies of the  Daphnia when viewed under ultraviolet light.

B.     Before the lesson:

1.     Order the sugar-dye compound from a chemical supply  house such as Sigma. Order
       Daphnia magna from a biological supply house such as Carolina.  Time the shipping of this
       order so you can do this activity soon after the Daphnia arrive.  Check to make sure the
       openings on the pipets are large enough for Daphnia to pass through.  If necessary, you
       can cut plastic pipets to make a larger opening or use turkey basters.

2.     Set up a safe, black-light viewing station.

       Safety note:   UV  light is harmful to  the eyes.  You  can use UV light safely with a
       commercial viewer, or you can construct your own.  The object is to limit room light and
       prevent students from looking directly at the UV bulb.  One way to do this is to cut a
       window in a cardboard box and place the UV bulb below the window in such a way that the
       sample will be illuminated, but students cannot view the bulb.  The sample can be placed
       on a small stand inside the box to bring it closer to the height of the window.

3.     Prepare the sugar-dye solution.  The sugar-dye compound will come in crystalline form.
       To mix the solution, get a plastic 1-liter bottle and mix 500 ml of lake water to 1  gram of
       crystal sugar-dye compound. Put on the cover and shake well.  Shake the solution each
       time before you use it because the sugar-dye does not mix well with water. Label and
       store this in the refrigerator.

4.     Prepare a vinegar solution by putting 3 ml of vinegar in a container and adding lake or
       aged tap water to make a total of 600 ml.

5.     The next task is to prepare a series of solutions,  each more dilute than the previous one.
       You may make this yourself ahead of time, or do it with  the students.  Student directions
       are given in the "Wth the Students" section. Following are directions for you to make the
       proper concentrations ahead of time.  Take 600 ml of the vinegar solution, pour out 300
       ml in a beaker or jar, and call it treatment #5. Add 300 ml of lake water to the original
       container and stir.  Pour out 300 ml into a new jar, and this is treatment #4. Add another
       300 ml of lake water to the original container and pour half out again.  This is treatment #3.
       Continue the procedure for treatments 2 and 1.

C.     With the students:

1.      Introduce the idea of a toxicity test using the background information.  Ask the students
       if they can list ways that a chemical can harm a living organism other than killing it. Show
       the vinegar, and introduce the idea of acidity as a pollutant.

2.      Introduce Daphnia. Emphasize that we have no desire to hurt these creatures,  but that
       there is always the possibility that individuals will be hurt or killed in handling. The small
       amounts of vinegar we are using are not expected to kill Daphnia but may upset them
       enough that they do not eat for a while. The Daphnia are expected to  recover.

3.      Introduce the sugar-dye using the background information.

4.      Each group of 4 students should get 6 baby food jars, a supply of vinegar solution, and a
       supply of lake water. Label one jar "c" for control. Explain  that the control jar will have no
       pollutant (vinegar) in it.  A control is the part of an experiment that represents what would
       happen under normal conditions. Label the other jars "treatment 1" through "treatment 5."
       A treatment is a variable added to an experiment to see what effect the  variable will have
       on the experiment.  Our variable is the amount of vinegar we add to the water.

5.      Now have  students fill their labeled jars with different concentrations of vinegar solution.
       In the jar marked "c", measure out 30 ml of lake water (no vinegar solution).  Now we need
       to add a known amount of pollutant to the water. If you have prepared the treatments
       ahead of time, show students the vinegar solutions,  and explain how you made them.
       Have students transfer 30 ml of each treatment into the appropriately labeled jar.

6.      If you would like the students to prepare their own  dilution  series, you can go through the
       following procedure step by step with the students.

             a.      In jar #5, add 30 ml of the vinegar solution.
             b.      In jar #4, add 16 ml of vinegar solution and fill to 30 ml with lake water.
             c.      In jar #3, add 8 ml of vinegar solution and fill to 30 ml with lake water.
             d.      In  jar #2, add 4 ml of  vinegar solution and fill to 30 ml with  lake water.
             e.      In jar #1, add 2 ml of vinegar solution and fill to 30 ml with lake water.

7.      The next portion of the lesson takes 30 - 45 minutes. You can stop here, and resume the
       lesson within a week. The students should cover their containers.

8.      In the next stage,  students add 5 Daphnia to each of the 6 jars. Demonstrate how to add
       Daphnia to a  solution as follows:  take up Daphnia from a beaker in a pipet.  Put  the end
       of the pipet below the surface of the solution you are adding it to and gently squeeze the
       Daphnia out of the pipet. If a Daphnid is exposed to air, it will get air trapped underneath
       its outer covering (called a carapace)  and will float on the surface. If a Daphnid floats or
       does not move, it has been injured during the transfer.  Replace it with  another Daphnid.
       Keep the water and container that the Daphnia were shipped in to serve as a recovery
       tank for them until the end of the experiment.

9.     Allow Daphnia to swim in the treatments and control jars for 30 minutes.  Observe. Then
      add approximately 10 ml of the sugar-dye solution to each of the 6 jars and let the Daphnia
      feed for 15 minutes.

10.   Explain to the students that the sugar and the dye are connected in the water in such a
      way that we cannot see the dye. The Daphnia eat the sugar-dye and break the connection
      between the sugar and the dye, which then makes the dye visible in the transparent bodies
      of the Daphnia when viewed under ultra-violet light.

11.   Observe the Daphnia under UV light using a commercial viewer, or by placing the UV bulb
      inside a box that has a window cut in it, so you can view the jars but not look directly at the
      bulb.  Count the numbers of glowing Daphnia in each jar and note their activity.  Fill  out the
      observation sheet  (Figure 3-1).  After viewing and recording, remove the  Daphnia from
      their treatments, and place them together in the container they came in.

12.   Have groups experiment with ways to graph their data. One effective graph places the
      number not glowing on the vertical axis and uses bars for each treatment and the control.

13.   Make sure it is clear to the students that the Daphnia that were glowing were those that
      ate the most sugar-dye compound.  Why did some of the Daphnia not eat? Discuss how
      "sick" Daphnia can affect the health of the food chain.

14.   Clean up: all  used liquids may be  poured down the drain. Daphnia  may be retained as
      classroom or household pets in small aquaria (see Raising Algae and Water Fleas) or
      disposed of.

Group Names:
Observation of Daphnia (include the activities of the Daphnia and the number of Daphnia glowing):

Control Jar
Treatment 1
Treatment 2
Treatment 3
Treatment 4
Treatment 5
Room Light

Not Moving

UV Light

Not Glowing
(or glowing more faintly
than controls)

Figure 3-1.  Data sheet; effects of a pollutant on Daphnia.

                           YOU ARE WHAT YOU EAT

       Overview:  Students experiment with fat-soluble versus water-soluble dyes as models
       for contaminants.

       Objective:  To demonstrate how a chemical can bioaccumulate in an organism.

       Materials for 28 Students:   Red food coloring; red oil-based artist's paint; 500 ml
       mineral oil or baby oil; water; 23 baby food jars; 14 pipets; two large paper fish cut-outs.

       Teaching Time:  45-eo minutes.

Note:  This activity is planned for 28 students working in 7 groups of 4. It can be easily modified
for more or fewer students.

Teacher Instructions

A.     Background information:

       Many of our present water pollution problems result from very small amounts of many
different kinds of chemicals in water. Some of these chemicals are considered toxic because they
are poisonous in very small amounts (parts per million, billion,  or trillion).  One part per million is
one drop in a swimming pool.  The toxic nature of a chemical is determined through a test called
a toxicity test.  The discharge of chemicals with high toxicity into fresh water is regulated so the
amount of chemical does not exceed the amount that will harm organisms.

       A relatively new water  pollution concern is that some chemicals have a tendency to
bioaccumulate. Bioaccumulation is the "building-up" of a chemical to a toxic level in an organism's
body.  The chemical may occur in the water in such minute amounts that the water is not harmful.
However, when the chemical is  taken in by organisms, they may not be able to excrete it, and it
builds up in their bodies. When these organisms are eaten by others higher on the food chain,
they pass on their toxic dose more concentrated than before. The term bioaccumulation is often
used  interchangeably with the term bioconcentration (accumulation  from  water only) and
biomagnification (accumulation  through the food chain).

       A chemical is more likely to bioaccumulate if it is not very  water soluble (meaning that it will
not dissolve easily in water). If it is not water soluble, it is probably fat soluble (will  dissolve in fat).
Small amounts of chemicals that are water soluble, even if they are  toxic, may be taken into the
digestive system of an animal, dissolve, and pass out again in the wastes of that animal.  Likewise,
chemicals that are fat soluble will also be taken into the digestive system.  However, fat-soluble
chemicals are often stored in the  animal's fat and will not pass out of the organism's body until the
fat has been used up. This is the problem of bioaccumulation.  The  chemicals accumulate in an
organism,  which in turn is eaten  by a bigger organism, which receives a  greater  dose of the
harmful chemical. Bioaccumulation can be a difficult concept to understand.  An excellent lesson
to use with this demonstration is found in WOW!: The Wonders of Wetlands. "Marsh Mystery."

B.     Before the lesson:

1.      Put some oil (enough for about 10 drops for each group of students) in a jar. Add some
       oil-based artist paint (it comes in a tube as a thick paste; do not use acrylic paint) into the
       oil  and stir it until it is smooth.  Label this jar "chemical A." Put some water (enough for
       about 10 drops for each group) in ajar. Add several drops of food coloring.  Label this jar
       "chemical B."  Try to  make the "chemicals" the same color and intensity.

2.      If desired, photocopy the zooplankton drawing at the bottom of this page to make 14 small
       drawings (see student step 2).

3.      Each group will require:  paper towels, 2 pipets, 3 baby food jars, marker, and water.
       Since oil paint and food coloring can be messy,  spread each station with towels, and have
       students wipe  up spills  immediately.

C.     With the students:

1.      Tell the students that our water supply has thousands of chemicals in it.  Some of these
       chemicals are potentially dangerous to the plants and animals that live in the water and the
       animals that eat the plants and animals in the water. Near the base of the food chain are
       the primary consumers, also called zooplankton. Primary consumers eat plants and are
       eaten  by other animals.  Daphnia (a type of  water flea) is an example of zooplankton.
       Today we are going  to see how chemicals can affect these zooplankton and the other
       organisms that depend on zooplankton for food. Assemble groups of 4 students each.

2.      First, have each group of students make 2 tiny (1") zooplankton pictures. These will serve
       as  "labels" on  the zooplankton models the students will be making. You can use a  field
       guide  to ponds (i.e., Pond Life) as a reference and  have students draw them, make
       imaginary organisms, or simply cut out the zooplankton at the end of this lesson (Figure

3.      Give each group 3 baby food jars and have them put about 2 cm of water and 2 cm of oil
       in each container (1 cm = about 1 pinky width).  Tape a picture of a zooplankton to each
       of the jars.  Label one jar 1 and the other 2. Label the third empty jar "waste."

4.      Tell the students that all living things are made up of water and fat (oil). The model that
       they have just made represents the fat and the water in the body of a zooplankton, and it
       will help us to  understand how a chemical can bioaccumulate.

5.      Show the students chemical A and chemical B.  Explain that, for this lesson, they represent
       dangerous chemicals. Also explain that although they look the same, they do not act the
       same in the body of a living  organism. Chemical B is considered highly toxic  or dangerous
       to organisms. A toxicity test to assess this danger was run, and it was determined that 3
       drops  of  chemical B will  kill a zooplankton.  Chemical A is not highly toxic.  It  was
       determined that 6 drops of chemical A will kill a zooplankton. There are equal amounts of
       chemical A and chemical B  in the lake where our zooplankton live but not enough  to harm


6.     A zooplankton can get chemicals in its body by eating small plants that have the chemical
      in it or by taking it in from the water.  Tell the students to carefully add two drops of
      chemical A to jar 1 using one pipet. Then using the other pipet, add two drops of chemical
      B to jar 2. Note:  introduce chemical B below the line between the oil and water.

7.     Gently swirl each of the jars and  observe what happens (chemical A will mix with the oil
      and chemical B will mix with  the water).  Again, remind the students that although all
      chemicals can be dangerous to living organisms, there must be enough  of the chemical
      there to harm it. In our experiment, two drops of either chemical is  not enough to kill or
      harm the zooplankton.

8.     Explain to the students that, in a living organism, water is constantly taken in and then
      expelled through its wastes.  Fat (oil) is taken in and stored in the body.  To model this,
      take a pipet and have each student carefully draw up the water (the lower layer)  in each
      jar and put it into  the "waste" jar.  To have the  zooplankton "drink," replace the liquid
      withdrawn with fresh water. Be sure to leave the oil layer in the jar.  How many drops of
      chemical are in jar 1? (2) Put two marks on the zooplankton on jar  1. How many drops
      of chemical are in jar 2? (0) Don't put any marks on the zooplankton on jar 2.

9.     Add another 2 drops of chemical A to jar 1  and another 2 drops of chemical B to jar 2.
      Remove and replace the water once again.  How many drops of chemical are now in jar
      1 ? (4) Put another 2 marks on the zooplankton on jar 1.  How many drops  of chemical are
      in jar 2? (0) Don't put any marks on the zooplankton on jar 2.

10.   Explain that chemical A has collected in our zooplankton because chemical A is fat soluble
      (it will dissolve in oil). Chemicals that are fat soluble will bioaccumulate (build up in the fat
      of living organisms). In our demonstration, chemical A bioaccumulated in our zooplankton
      while chemical B kept passing  out with the wastes of the organism.

11.   Let's say there  are now 4 drops of chemical A in our zooplankton, but this is  still not
      enough to kill it.  It takes 6 drops  of chemical A to kill our zooplankton, but very few ever
      live long enough to collect 6 drops because they usually die or are eaten  by the time it
      takes to accumulate 6 drops  of chemical A. Why do we care if the chemical is in the
      zooplankton or not? It is not killing them or making them ill. The next step should reveal
      that this contamination could move up the food chain.

12.   Let's say two fish swim along and eat 12 zooplankton each. Six of these zooplankton have
      4 drops of chemical A in them.  Collect  12 zooplankton for each fish, 6 jar 1's and 6 jar 2's -
      you may want to put the jars by or on  a large paper cutout of a fish.  How many drops of
      chemical A does each fish have in  it? (24) Does it have any of chemical B  in it? (no) Let's
      say it takes 35 drops of either chemical to make our fish sick and 40 drops to kill it.   Do the
      fish look sick? (no)

13.   Let's say a local fisherman catches these two fish and eats them for supper.  How many
      drops of chemical A does he have in his body? (48) Let's say it takes 50 drops to make
      a human ill and 60 drops to kill him or her.  What happens if this person eats too many


14.    Ask the students which chemical was more harmful:  A or B? (A, because it dissolved in
      the oil, it was accumulated).  Examples of fat-soluble chemical contaminants include PCBs,
      DDT, and dioxin.  Following is a list of sources of chemicals that might bioaccumulate.
      Discuss this list with your class.

                   Food we eat that has been sprayed with insecticide so it looks nice.
                   Dairy products from cows whose hay  and other food have been sprayed
                    with herbicides.
                   Careless handling of chemicals (pesticides, paints, petroleum  products,
                    etc.) so they find their way into our food/water supply.
                   Eating fish from contaminated water.  Pollutants could come from runoff
                    from farms, lawns, and gardens as well as from industry.

15.    Cleanup: Wipe work stations and throw the towels.  Jars should be wiped out and then
      washed. Plastic pipets may be permanently stained.
Figure 3-2. Zooplankton cut-outs.

                                Cool, Clear, Water?

       Overview:  Students experiment with "indicator fish" that have litmus paper fins.

       Objectives:  To demonstrate that pollution can be invisible. To discuss some types of
       pollutants, their causes/effects, and some solutions to pollution problems.

       Materials for 28 Students: Three half-gallon or 2-liter sized glass or clear plastic jars;
       a half-gallon of muddy pond or river water; tap water; 1 Tbsp, or 10 ml, vinegar; 21 baby
       food jars; 21 plastic spoons; 21 narrow strips of litmus paper; picture of a lake or river; and
       7 copies of the student comment sheet (Figure 3-3).

       Teaching Time: 40-50 minutes.

Note:  This activity is planned for 28 students working in 7 groups  of 4. It can be easily modified
for more or fewer students.

Teacher Instructions

A.     Before the lesson:

1.      Obtain neutral litmus paper from a chemical supply house.  It is blue when immersed in a
       base and pink when immersed in an acid. Test the tap water and muddy water. For this
       experiment, they should both be basic, turning the litmus  blue.  If either one is acid, you
       can make it basic by putting in a pinch of baking soda.  Blue litmus will designate water
       that is suitable for fish in this experiment.

2.      Label the large jars 1, 2, and 3. Put muddy pond/river water into the jar #1. Put tap water
       in jar #2 and water with  a small amount of vinegar in jar #3. The amount of vinegar you
       need depends on your litmus paper; add just enough to  make the litmus turn pink.
       Designate pink as the color of litmus in "acid polluted" water.

B.     With the students:

1.      Work in groups of 4 students. Tell the students that we are  pretending that the only water
       they get to drink today will come from these three jars.  Each group should write on their
       comment sheets which jar(s) they would or would not drink from and why.  Now have
       students label  3 baby food jars 1, 2,  and 3. Distribute samples of the three waters to the
       appropriately marked student jars.

2.      It is never safe to test unknown water for drinkability by tasting it. But sometimes animals
       can be used as "detectors" of pollution in water. We will not be using a real animal, but we
       will use an "indicator fish" that is very sensitive to acid in the water.  Each group can now
       make 3 of these "indicator fish."  Make each fish from a plastic spoon by taping one or
       more litmus paper fins to the convex bowl of the spoon.  The handle of the spoon is the
       tail of the fish. Use permanent markers to draw eyes, gills, and mouth on the face of the
       fish.  Label the fish 1-3.

3.      Students can now immerse  their 3  indicator fish into the appropriately marked water
       container, making  sure the litmus fins contact the water.  Students should record the
       results on their comment sheets.

4.      Discuss the results. Students should have observed that the water in jar #3, although it
       appeared "normal", affected the  litmus fins so they turned pink.  If acidity was  the only
       pollutant we were  concerned about, our indicator fish with  litmus fins would be good
       pollution detectors.  Ask the students if they changed their minds about which jars  of water
       they would choose as their drinking supply.  Ask them to explain any changes of opinion
       on drinkability on their comment sheets.

5.      Hold  up a picture of a lake or a river. Ask the students if they think the water in  the lake
       or river is safe to drink.  Discussion should lead to the fact that you have no way of visually
       telling whether or not the water is safe to  drink or safe for fish and wildlife.

6.      In groups, have the  students brainstorm an experiment which would tell us whether or not
       the water is safe to drink.  Have each group share their experiment with the  class to
       determine the safety of the water. Try to encourage the students to come up with  creative
       solutions so they do  not merely replicate the demonstration  they observed in the three

7.      Using the chart (Table 3-1) as a  source  of information, discuss the different classes of
       water pollution, the  effects  and causes of the  pollution, and  possible solutions  or
       treatments. You may also want to bring up the cost of treatment and contrast it to  the cost
       of prevention.  You may want the students to become "experts" on one type of pollution
       and then report to  the class about that type. Also ask the students if they believe it is
       possible to make water "pollution  free."
       POLLUTION:  Just because you can't see it doesn't mean it isn't there!


At first sight, which of these jars would you be willing to have as your source of drinking water for
the day?
At first sight, which of these jars would you NOT be willing to have as your source of drinking water
for the day?
What happened to the litmus paper fins of the "fish" in jar #1?

Jar #2?

Jar #3?
After making observations, which of these containers would you now NOT be willing to have as
your source of water for the day?
Our experiment for testing whether or not the water in the lake is safe to drink is:
Figure 3-3. Student comment sheet; cool, clear water.

Table 3-1.  Water pollution and its effects on fish.
 Types of Pollution
 Heavy Metals
 Organic Pollution
 Pesticides (a type of
 organic pollution)
 Acid Rain
  Deformities of heart
  Deformities of the
  yolk sac of young fish

  Thick gills
  Internal bleeding
  Slowed growth

  Build-up in tissues
  Retardation of
  development (due to
  lowered oxygen
  levels, etc.)

  Fused vertebrae
  Build-up in tissue
  Fin erosion
  Eggs of larvae on the
  bottom of river may
  be covered and
  Decreased food
  production at base of
  the food chain
  Undesirable species
  take over

  Fish stop  eating
  Reduced  ability to
  Kills immature fish
 Waste heat from
 power generation
 Clear cut of trees
 around the stream

 Non-point sources
 Point sources from
 industry & mining

 Runoff from farms
 Feed lots
 Manufacturing wastes
  Runoff from farms,
  lawns, golf courses,
  Misuse of pesticides
  Road building
  Urban construction
 Air pollution
 Poorly buffered water
  Cool water with
  cooling tower
  Leave strip of trees
  growing along banks

  Treatment at a
  sewage plant
  Industrial water

  Treatment at a
  sewage plant
  Prevent runoff from
  Recycle batteries

  Prevent runoff from
  Don't overuse on
  lawns and farms
  Use when dry

  Improved land-use
- Control industrial
- Burn less fossil fuels
  in cars, etc.

                                 Pollution Munchers

       Overview:  Students compare the bacterial activity between sterilized and unsterilized
       "polluted" water. Bacteria from the unsterilized jar are then introduced to eat the "pollutant"
       in the sterilized jar.

       Objective:    To  conduct an experiment that will demonstrate  some aspects  of

       Materials:  2 drops octanol (capryl alcohol); 2 liters fish tank water;  2 coffee filters or 2
       pieces of filter paper; 2 1-liter beakers; 2 glass stirring rods; funnel; Bunsen burner or hot
       plate; safety glasses; protective gloves.

       Teaching Time:  Approximately 40 min. of one class period then 5 min. daily for 2-3
       days, 10-20 min. of another class period then 5 min. daily for another 2-3 days.

Note: This activity is partly demonstration, partly student activity.

Teacher Instructions

A.     Background information:

       Recent tests show that  techniques using bacteria and  other microorganisms to "eat"
hazardous waste may be a promising solution for disposing of many organic wastes and cleaning
up contaminated water.  This approach is one form of "bioremediation." Bioremediation is the use
of living organisms to clean up oil  spills or remove other pollutants from soil, water, or wastewater.
       Bacteria are microscopic organisms found in all domains of the planet. They are so small
that about 200 bacteria will fit across the "thickness" of your thumb nail.  All water bodies that
support life have their own unique microscopic organisms living in them.  A few kinds of bacteria
cause diseases,  but most of the bacteria in the water are helpful. Bacteria break down organic
materials (materials made out of carbon) into smaller parts, which means they can decompose and
recycle dead organisms and other materials in the water.  Some can  actually break  down
hazardous organic waste into harmless parts.

       To use bioremediation at a site, we must first learn about the wastes in the site to see if
they might  be  safely  broken down  by  microorganisms.   At  many  contaminated  sites,
microorganisms  that break  down organic wastes  have naturally  developed over  time.
Bioremediation generally starts by collecting and isolating these microorganisms to determine what
nutrients and climatic conditions (like acidity, temperature,  and oxygen levels) enhance their ability
to break down the contaminant. Often, the microorganisms can then  be transferred to other sites
contaminated with the same wastes and stimulated to do the job there.

       In this  lesson, the students will use bacteria from fish tank water to demonstrate the
concept of bioremediation.  The  bacteria will  eat  a  non-dangerous "pollutant"  and then be
introduced to a sterilized area, where the "pollutant" also occurs, to see if they eat the pollutant
in the new location.

       The "pollutant" we will use is 1-octanol, also called capryl alcohol. It is a good model for
us to use because it is safe for us to handle using normal precautions.  The bacteria in our lake
water can use octanol as food with no ill effects, and small amounts can be disposed of down the

B.      Before the lesson:

1.      Obtain a very small amount of "1-octanol" from a chemical supply house such as S/gma.
       You need only 2 drops for this experiment,  but you may have to buy more.  It is very
       inexpensive.  It is called octanol because it is a chain of 8 carbons.  The "ol" suffix is
       because it is a type of alcohol. It has a sweet smell.

2.      Obtain two 1-liter beakers of water from a fish tank. Goldfish water is very effective. Label
       one beaker "A" and the other beaker "B."

       Safety note: Review chemical handling procedures and set out protective equipment.  Use
       safety glasses, a lab coat or smock that is laundered after the experiment, and rubber
       gloves.  Do not allow any experimental chemical to touch your skin or lips, and do not allow
       food around chemicals. The small amount of octanol this experiment requires is safe to
       handle  in the classroom, but students should learn how to use protective equipment.

C.      With the students:

1.      Use the background information provided to introduce the topic of bacteria and their ability
       to break down organic materials, including some types of pollutants.  Introduce octanol as
       a "pollutant" for the purpose of this experiment, and demonstrate the protective gear you
       use. Octanol is not actually a problem in the environment.  Explain that we will use the
       octanol to "pollute" some fish tank water, and then see if there  is any evidence that the
       existing bacteria can eat the octanol. If they  do, we can then put these bacteria into
       sterilized fish tank water (without bacteria)  to see if the introduced bacteria eat the octanol
       in the new location.

       Show the two beakers of fish tank water, and explain where you got them.  Explain that
       each of these beakers has natural bacteria growing in it, but the bacteria are too small to
       see without a microscope. However, bacterial activity makes water cloudy or "cobwebby"
       so we can use these signs as evidence that bacteria are active.

       Safety note: The next step uses heat.  Be sure that the container you use is safe for direct
       heating. Use  hot pads or holders.

2.      Put beaker "B" over a source of heat and boil it for 3 minutes.  Immediately cover it and let
       it cool. Also sterilize a glass stirring rod in boiling water. When beaker B is cool, carefully
       lift the lid slightly, add 1 drop of octanol, stir with the sterilized rod, and cover tightly to
       prevent introducing new bacteria to beaker B. Also add 1 drop of octanol to beaker A and
       stir, but do not cover it so the bacteria have access to air.  In our scenario, both beakers
       are now "polluted."  Put the beakers aside in a warm place and observe daily. After 48
       hours, the bacteria in  beaker A should have multiplied so much that you can observe
       cobwebby bacterial growth or at least cloudiness.  If there is no evidence of bacterial
       growth in 2 days, leave the experiment another day or two. If you leave it longer, you may
       observe bacterial growth in beaker B from accidental reintroduction of bacteria.

3.      Discuss why beaker A shows bacterial growth (bacteria are breaking down the octanol)
       while beaker B is clear (there are no living bacteria there to break down the octanol). In
       our conceptual model of bioremediation, this is the case where naturally occurring bacteria
       have been discovered that can break down a pollutant. The next step would be to see if
       these helpful bacteria  can be introduced to a polluted place where the bacteria do not
       occur (beaker B).

4.      Using gloves, take beaker A and put the contents through a funnel lined with filter paper.
       Take out the filter paper and let it dry. Bacteria will be trapped on the filter paper. Bacteria
       are well  adapted to surviving a dry period.

       Safety note: There is no reason to think that fish tank bacteria would be dangerous,
       however, it is good practice to observe good hygiene including keeping hands out  of the
       experimental water and using gloves to handle the beakers.

5.      When the filter paper is dry, cut out the center of it. Put the center of the filter  paper into
       beaker B.  Leave uncovered and observe for 2-4 days.  If the introduced bacteria are
       breaking down the octanol, beaker B should become cloudy or cobwebby.

6.      Explain  once again that bioremediation makes use of naturally occurring or introduced
       microorganisms to break down contaminants. But before bacteria can be produced for this
       purpose, there  must be many tests to make sure  there  will  not be any dangerous
       consequences of their release into the environment.

7.      Cleanup: The beakers may be emptied in the sink and washed in hot soapy water.

8.      There are many enrichment possibilities for this activity.  Bioremediation is a rapidly
       expanding field, so students should ask a media specialist for suggestions on finding more
       information on it.

                                  Pea Soup Ponds
                       (Adapted from Lacustrine Lessons, 1984)

       Overview:  Students grow  algae with different concentrations of fertilizer to see the
       effect of nutrients on algal growth.

       Objective:  To show how algae can become a problem if too much grows in a pond or

       Materials for 28 Students:  28 baby food jars; hot tap water that has been aged for
       one day; 7 eyedroppers; algal culture; commercially packaged  plant fertilizer pellets or
       loose fertilizer (any type of commercial plant food may be substituted); artificial light source
       - preferably fluorescent;  masking tape or wax pencils.

       Teaching Time:   45-50 minutes one class period,  5-10 minutes during the next 4-5
       class periods.

Note:  This activity is  planned for 28 students working in 7 groups of 4.  It can be easily modified
for more or fewer students.

Teacher Instructions

A.     Background:

       Algae are often called plants  because they are green  and do photosynthesis, but under
most classification schemes, they are neither plants nor animals but are protists. When dissolved
nutrients, such as nitrogen and phosphorus found in fertilizers  and waste products, are added to
a lake, algae can grow very quickly. The lake turns greenish, and the situation is called an algae
"bloom." When the algae die in large numbers, which can be noticed by the presence of a strong
odor,  the real problems begin.  As bacteria start to decompose the dead algae, oxygen is used
up.  This often leads to dangerously low concentrations of oxygen which is needed for the survival
of other organisms such as fish. This happens even more rapidly in the winter, when the lake is
covered with snow and ice, because the lake water is too dark for algae to produce much oxygen,
and it is not in contact with air that could replenish its oxygen.

       Algal blooms  can greatly  speed up "eutrophication", the natural aging process of the lake.
Algal  blooms can be controlled by preventing the release of excess  nutrients into surface and
groundwater.  This  can be achieved by pollution control regulations and by efficient sewage
treatment facilities.

B.     Before the lesson:

1.      Order the algal culture ahead of time from a biology supplier (see Sources of Supplies at
       the end of this document). Make 7 copies of the algae growth chart (Figure 3-4).

2.      Purchase fertilizer. It is simplest if all students use varying amounts of the same fertilizer.
       However, an extension of this lesson is to compare different types of fertilizers, such as
       liquid versus dry, "organic" versus synthetic, and fertilizers with different concentrations of
       nitrogen and phosphorus.

3.      Prepare culture water by drawing 1 gallon of hot water from the tap and letting it stand for
       1 day.

C.     With the students:

1.      Discuss algal  blooms with the students, including common  causes,  referring to the
       provided background material. Explain  that each group will have 4 identical jars of water
       and algae, and that their job will be to experiment to find the effect of fertilizer on algae.
       An important point that students may miss is that 1 of the 4 jars should be a "control," that
       is, it should be a reference against which the other jars can be compared.  The control jar
       should have a concentration of zero, meaning no fertilizer should be added.

2.      Break into groups of 4 students. Each student should have his/her own jar.  Number each

3.      Introduce the fertilizer to be used, and determine how it should be measured (for example,
       eyedroppers full  for liquids, teaspoons for dry fertilizer, or numbers  of pellets).  Groups
       should plan their own experiments  by selecting 4 different fertilizer concentrations (one
       being zero).  Within the class, there should be a broad range of concentrations.

4.      Label the jars with masking tape or wax pencils.  Include the group number, student's
       name, and amount of fertilizer to be added. Have the students add fertilizer first, then fill
       with aged tap water to within a centimeter of the top.

5.      Add one eyedropper full of algae to each sample jar.  Leave jars uncovered.

       Safety note: Practice good hygiene and have students wash their hands after handling
       fertilizer or algae.

7.      Place all jars in areas with similar light intensities.  An artificial light source may be needed.
       Make sure the source of light is held constant for all jars. Dark at night is fine.

8.      Have students observe their jars  daily for any visual evidence of algal growth.  Keep
       records on the algae  growth charts or in experiment log books. After about three days,
       algae growth should become obvious as indicated by an increased "greenness" in the jars
       and possibly odor.

9.      At the  end of one week, have students fill out the "growth  after 1 week" section of the
       algae growth chart.  The members of each group should work together to decide how the
       algal growth in their control jar compares with their other jars. They may also record any
       other observations on their growth  chart.

10.     Discuss ways the data could be presented.  One way would be to use water color paints
       or crayons to  color in  a square for each fertilizer concentration, showing  that each
       concentration resulted in a different shade of green.  There are many other options.

11.     Have groups present their results.  Did different groups have similar findings?

12.     Ask if students observed any dead algae on the bottom of their jars.  If yes, what will
       eventually happen to the algae? Would this be good or bad for animals living in the water?

13.     Conclude by discussing with students why this excess of algae can be harmful to our
       lakes.  Are there any practices students have seen that could contribute to this problem?
       Ideas include fertilizing lawns, fertilizing just before rainstorms, and throwing or sweeping
       organic matter like leaves or grass clippings in the lake.  Are there actions students could
       take that would  improve the situation?  Some positive actions would be reducing or
       eliminating lawn  fertilizer, using a different fertilizer (low  phosphorus), or composting
       organic matter.

14.     Clean up:  The algal cultures should be poured on the ground,  especially in areas that
       could use fertilizer. Avoid adding the cultures to surface water.  If you pour them down the
       drain, they may burden your sewage treatment system.

16.     Enrichment activities:

             Compare  different fertilizers.
             Try varying temperature while keeping the nutrient concentration constant.
             Visit a lake or pond to look for evidence of algal blooms.
             Test the oxygen concentration of the water, before and after the algal   blooms,
             with a water test kit.


Day 1

Day 2


Day 4

Day 5


Growth Compared to Control Jar After 1 Week



Additional observations: color, odor, etc.
Figure 3-4. Algae growth chart.

                                    Chapter 4
                            Collecting, Sampling, and
                           Keeping Aquatic Organisms
       Living organisms can be an exciting addition to any classroom - they fascinate students
and give the room "atmosphere." Of course, plants and animals are also learning tools. However,
many classrooms do not have living organisms in them because of time  constraints, lack of
knowledge, or lack of funds.

       The following section contains ideas that will make organisms in the classroom a possibility
for many teachers who never thought it could be achieved. Ideas include a  variety of collection
methods (for both teachers and students), how to maintain classroom cultures, and how to build
inexpensive equipment for maintaining cultures.

                              AQUATIC SAMPLERS
                      (Adapted from Lacustrine Lessons, 1981)

       Overview:  Students make and use aquatic sampling gear.

       Objective:  To create useful aquatic sampling equipment from common, inexpensive

       Materials for 28 Students: Preparation for sampling trip: 7 coffee cans (three-pound
       size); 7 plastic bleach bottles (one-gallon size); 4 pairs of old nylon stockings or pantyhose;
       21 half-gallon milk cartons; 7 scissors; 7 small jars (such as baby food jars); about 140 feet
       of lightweight rope; string; 7 hammers and nails; 7 staplers; 7 weights (such as an 8 oz.
       fishing weight).

       During  Sampling Trip:  21  white plastic cups such  as  soft margarine cups;  7
       notebooks; pens and pencils; 7  rulers; identification books such as Pond  Life: 14 hand
       lenses; 14 forceps; 14 pipets or turkey basters; 7 sieves or pieces of window screen for
       sorting bottom samples; 7 white enamel pans or white plastic dishtubs; 14 plastic buckets;
       1 small tarp or large piece of heavy plastic.

       Teaching Time:  60 minutes to make equipment, at least 60 minutes for field trip, 45
       minutes for classroom work.

Note:  This activity is planned for 28 students working in 7 groups of 4. It may be easily modified
for more or fewer students.

Teacher Instructions

A.     Background information:

       There are many interesting organisms to be found in the shallow water along a lake shore
or pond. With the use of homemade sampling equipment, students can be introduced to a world
of diversity in a small aquatic environment.

       This lesson consists of two parts:  1) constructing aquatic sampling gear from common,
inexpensive  items, and 2) using the gear to explore shallow water.  See the next section on
active/passive collection methods for  more ideas on sampling techniques.  The  sense of
achievement gained by the students in making and successfully using their own equipment can
be a valuable by-product of the lesson.

B.     Before the lesson:

1.      Ask the class to collect the materials  listed above.

2.      Make 7 copies of the instructions for making the equipment.


3.      Select a sampling area that seems rich in life.  There should be vegetation in the water -
       swimming beaches are not good for this activity.

       Safety note:  Choose an area of lake shore or pond that has a gradual slope where the
       students can walk and wade safely.  Be sure the site  is free  of poisonous plants,
       underwater drop-offs,  broken glass, etc.  Prepare permission slips for the field trip.
       Arrange for an extra adult for every 8 students for the sampling trip.

C.     With the students:

1.      The first part of this lesson is the construction of the equipment.  Divide the class into
       groups of 4 each. Explain that each group will make sampling equipment from the items
       they collected. They will then use the samplers to collect aquatic organisms. Each group
       will make a nylon plankton net, a bottom scraper, and two or three observation chambers.

2.      Give each group 2 copies of the instructions for making samplers. It will help the students
       a great deal if you  have pre-made examples of the equipment.

3.      Have one pair of students  in each group make the plankton net and one pair make the
       bottom scraper. They can use the remaining time that they have to make the observation
       chambers. Give the groups 45-50 minutes to make their equipment.

4.      Prepare the students  for the sampling  trip.  It is very important that students  dress
       appropriately by wearing jeans, with  pant legs that can be rolled to the knee, or shorts,
       having a spare pair of shoes to wear in the water, and bringing a set of dry clothes, shoes,
       and a towel.

5.      The next part of the lesson  is the field trip.  Warn students of possible hazards, and give
       directions for safe and respectful sampling.

       Safety  note:   Students should  never sample barefooted.  Define the boundaries  the
       students are to work within.  Students should stay in shallow water - less than knee deep;
       don't throw stones, no pushing,  be respectful of animals captured.

6.      Demonstrate the use of each piece of equipment.  The bottom scraper should be tossed
       out using an underhand throw. It works best in soft mud or loose sand.  Larger organisms
       can be found by filtering the contents through a sieve or piece of window screening and
       then turning out the contents of the sieve into a white enamel or plastic pan. Add enough
       water  so organisms can float out, and pick them  up with forceps and pipets or turkey
       basters. The organisms can be placed in margarine tubs with lids or in the plastic buckets
       for carrying.

7.      The plankton net should be pulled through the water.  If the bottom  is soft, it can be
       carefully tossed out underhand and then pulled in. If the bottom is rocky, the jars might
       break.  Pull the net through the water several times. Water will pass through the  mesh of
       the nylon while small organisms will be trapped in the jar. Empty the jar into a margarine
       tub or plastic bucket for carrying.  Do not  use the plankton net in areas where it could
       become entangled in debris.

8.      Explain to the class that they have an opportunity to examine the diversity of life in their
       sampling site.  Give the groups 30 minutes to find as  many different aquatic organisms
       (plants and animals) as they can find in their area.

9.      Spread the groups out so there is 15-20 feet between each  piece of equipment.  Extra
       adults can watch for potential safety problems. Instruct each group to divide into pairs:
       one pair using the bottom scraper and one pair using the plankton net (later they can

10.    Have the groups keep examples of the different organisms in their observation chambers
       to show to the whole class later.

11.    Remind the groups to carefully check the rocks, sticks, and large plant masses for small
       animals.  They might want to rinse these items off in a sieve or piece of screen to find the
       organisms.  Another technique is to lay wet wood and other objects on a tarp or large
       sheet of plastic.  As the wood dries, organisms will become evident as they move about.
       Put organisms into a margarine tub or plastic bucket for carrying.

12.    After 30 minutes, call the groups together and ask each  of them to tell how many different
       plants and animals they found.

13.    Compare the results.  Did some find more than others? Was this due to any differences
       in location? Have some individuals describe or show some of the organisms found.  Did
       everyone else find the same thing?  Where was the organism found?

14.    At this point, samples can be brought to the classroom in plastic buckets or returned to the
       water.   Drawing and note  taking can be done pondside but is  much easier in the
       classroom. Provide Pond  Life identification books (see Appendix B)  for those who would
       like to identify their plants and animals.

15.    Clean up: At the end of the activity, all organisms should be released into the water where
       they were found.

16.    Summarize the sampling expedition.  Point out that there were many small organisms to
       be found in an area that initially did not appear to be that rich in life forms. Remind them
       that different animals were found in different locations  and habitats.

17.    Conclude by pointing out that the diversity of species found in an area depends  on  a
       variety of factors. This could include temperature and light differences, availability of food,
       the variety of niches or habitats available, or even variations of water quality.

Nylon plankton net
Materials:  Plastic bleach bottle, nylon stocking, 4
one-foot-long strings, small jar (e.g., baby food
jar), scissors, light rope, small  rubber bands,
1.  Using scissors, cut the bottom  1  inches out of
a plastic bleach bottle and discard.  Next, cut the
plastic bleach bottle into three parts, creating a
bottom ring and  middle ring each 2  inches wide
and a top portion that is shaped like a funnel.
2.   Cut the stocking so that only the leg remains.
                  Discard Bottom
3. Bring the stocking leg through the bottom ring
and then fold it over the outside.  Cut the side of
the middle ring, open it and  place  it  over the
bottom  ring and nylon stocking. Securely fasten
it in  place using staples  or glue.  Puncture the
sides of the  rings in  4 places equidistant from
each other. Loop  and tie one string in each hole.
Bring the other end of the 4 strips together and tie
a knot.
                                     4.  Insert the funnel  near the other end of the
                                     stocking.  Fasten the  stocking around the mouth
                                     of  the  funnel  using  small   rubber  bands.
                                     Remember to leave about five inches of stocking
                                     loose at the bottom end.
                                     5.  Fasten the loose end  of the nylon stocking to
                                     the  mouth of the small  jar using small  rubber
                                     6. Attach the rope to the knotted strings to form a
                                     towline  for the constructed plankton net. A small
                                     weight  may  be  attached  to  the  towline  if

                                     Observation chambers
                                     Materials:   half-gallon milk cartons,  scissors,
                                     1. Staple the pouring spout closed.
                                     2.  To  make  a chamber with a  hinged lid - cut
                                     three sides of the carton wall which is on the same
                                     side as the stapled pouring spout (see diagram).
                                     This type of chamber is good for holding light-
                                     sensitive animals.
                                     3.  An  open-top chamber can  also  be made -
                                     simply cut all four sides of the carton wall on the
                                     same side as the stapled spout,  and  remove the
                                     carton wall.
                                                    Bottom scraper
                                                    Materials:  coffee can, hammer, nail, light rope.
                                                    1.  Punch out 15 holes in the bottom of the can,
                                                    using a hammer and a nail.  Punch one hole on
                                                    each side of the can near the top directly across
                                                    from each other.
                                                    2.  Tie a weight (an 8 oz. fishing weight works
                                                    well) to loop in a piece of line that is tied tightly
                                                    between the holes near the top of the can.
                                                    3.   Tie the tow  rope to the same  loop as the
                                                    weight, and the bottom sampler is ready to use.
Figure  4-1.
Equipment  construction  for  water

                         Active/Passive Collection Methods

       Overview: This is a teacher preparation activity.

       Objective:  To give teachers a variety of methods to use when collecting freshwater
       specimens for the classroom.

       Materials:  Vary from method to method.

       Preparation Time:  varies.

Teacher Instructions

A.     Background information:

       Some of the activities in this packet call  for the  use of live  organisms.   It has been
suggested that you purchase these organisms from  a biological supply company.  Another
possibility for getting live organisms for these activities, and others you may wish to conduct, is
to keep a "farm" of these tiny organisms in your classroom.  You can collect the animals for your
farm from a nearby pond, stream, or lake.  The following information deals with various collection
methods.  You can try several of these and adapt them  to best suit your situation.  Different
methods, at different times of the year, will  give you different organisms.

       There are two different kinds of collection methods:  active and passive.  Active collection
methods deal with going out and collecting  the organisms on the spot.  Passive collection deals
with placing some sort of apparatus in the water to which the organisms will attach.  After a period
of time, you collect the apparatus.  These methods can  be  carried out by one person, small
groups, or an entire class. Passive collection would be a better choice if you don't have a large
source of water around or if your source is  far away.

B.     Collection and viewing equipment:

Following are inexpensive items that are useful in the field:

             5-gallon plastic pails, used to carry water and materials
             pyrex or metal trays, such as cake pans, for picking through debris
             magnifiers, used for close examination
             jars, such as canning, salad dressing, peanut butter, etc. with covers
                    (If you wrap the jars with one or two circles of tape, there
                    is less danger of the jars shattering if they are knocked
                    together or dropped. Clear plastic peanut butter jars work
                    very well.)
             nylon strapping tape to reinforce pails if necessary
             smaller pails
             funnels to fill sample jars


             thermometer for field information
             marker (to write on glass)
             rubber boots, hip boots, or waders

C.     Specialized collection methods and equipment:

Following are methods used in aquatic sampling, along with more specialized equipment you can

Active Sampling methods and Equipment:

1.     Kick method. This is used in streams.  Kick or agitate a rock while holding a net down

2.     Rock or debris  picking.  This is used in streams or ponds.  Pick up a rock or debris and
       search for attached animals.  Large, flat rocks work best. Alternatively, place the debris
       on a plastic sheet by the shore and wait for animals to begin wriggling so they can be

3.     Netting.  Used in streams or ponds.  Use a fine meshed net to sweep animals directly out
       of the water. An aquarium net works well. You can also make a simple net by using a
       wood stapler to attach a 2' x 2' piece  of window screen to two 3' long 2" x 2" wood pieces.
       The wood pieces, on opposite sides of the screen, form handles.  This net can be rolled
       up for easy storage.

4.     Dipping.  Used best in ponds or slow streams. Use a cup attached to an extended handle,
       like an old fashioned water dipper.

Passive Sampling methods and Equipment:

1.     Stacked plates.  Used in streams or ponds. Obtain several square masonite boards of
       decreasing sizes.  The largest should be about 4" on a side.  Drill a hole in the center of
       each of the boards.  Place a bolt through the center and stack the boards smallest at the
       top, largest at the bottom.  Separate each board with up to 4 washers - different sized
       spaces attract different organisms.  Put a nut on the top of the bolt to hold the boards in
       place.  Anchor the apparatus to the bottom of the stream or pond with a stake and a nylon
       string.  Animals will seek out the spaces in the board or colonize the board  surface.  Leave
       it in the water for a few weeks.  After collection,  remove the bolt and scrape the plate
       surfaces into white pans, with a little water in them, so you can pick out the organisms.

2.     Nylon bag filled with leaves.  Used in streams or ponds.  Fill a mesh bag (such as an onion
       bag) with leaves. Anchor it to the bottom of the stream or pond. Check after 2 weeks by
       picking up the bag and swishing it in a pan of water to see what organisms have colonized
       it.  It can be replaced and checked later or opened and carefully picked through.

3.     Sponge. Used in ponds or streams.  Anchor a kitchen sponge to the bottom of the pond.
       Small organisms will crawl into the pores of the sponge. Squeeze the water out of the


       sponge, catching it in a white margarine tub, when ready to view.

4.      Drift net. Used in streams. The drift net will collect animals in a stream that are drifting
       along the water's surface and  beneath it.  You can  make one by attaching fine mesh
       netting to a sturdy frame. One side of the frame will sit on the bottom of the stream with
       part of the net and frame above the surface of the water. Anchor the frame to the stream
       bed.  Many insects drift along the surface of the stream in the evening hours so this net
       is most useful when left out overnight or collected in the late evening.

5.      Plastic strips.  Used in streams or  ponds.  Cut  a strip of heavy plastic into 1-inch strips
       about 3 feet long. Anchor the strip to the bottom of the stream and check after 2 weeks.

6.      Rope. Used in streams. Anchor a thick piece  of rope to the bottom of the stream and
       check after 2 weeks.

7.      Bricks.  Used in streams. Place red,  three-holed bricks on the bottom of the stream and
       check after 2 weeks.

8.      BBQ cage. Used in streams. Fill a metal cage  from a rotisserie with rocks.  Anchor it to
       the bottom of the stream.  Pull the whole works up every 2 weeks and examine the rocks.

D.     Sampling tips:

             Take a sample of the water from your collection site with you. If you choose to keep some
             specimens, they will be adapted to this water.

             Be careful not to over collect or to disturb the shoreline habitat.

             Make sure, while you are out  in  the field, that specimens you  collect do not heat up. An
             increase in temperature of greater than 10 degrees may kill the  organisms.  Cooling the
             organisms, as in a cooler with ice, is generally acceptable.

             Do not put specimens in water straight from  the tap. Tap water may have chemicals in it
             which will kill your specimen.  If you need to use tap water, you should use hot tap water and
             allow it to stand over night. You can also purchase chemicals from a pet store that will
             dechlorinate water.

             Have a pond/stream field  guide (see  Reference Section) on hand to identify unknown

             Quickly return specimens to the water whenever possible.

             Remind students to treat the pond/stream/lake, and the organisms found in and around it,
             with respect and with a sense of  responsibility.

             Organisms that you collect from a  stream  need flowing  water so your aquarium
             should be well  aerated.

             Pond animals are generally easier to keep in classrooms than stream animals.

                          Making a Classroom Aquarium
                     (Adapted from Project WILD - Aquatic, 1992)

       Overview: This is a teacher preparation activity.

       Objective:  To provide a method for making a classroom aquarium from inexpensive

       Materials: 5 pieces of glass; aquarium sealant.

       Preparation Time:  1-2 hours after assembling materials.

Teacher Instructions

A.     Background information:

       You can make  an inexpensive aquarium to hold fish, or any other organisms, in your
classroom.  If you have never had an aquarium in your classroom, a five- to ten-gallon tank (19
to 38 liters) is  recommended as a beginning size; however, this size will hold only a few fish.
Normal window-grade glass is suitable for five-gal Ion tanks, but bigger tanks should be made from
heavier (thicker) glass.

B.     Materials:

1.     Obtain glass from a glass shop. They will cut the pieces from glass of the weight you
       desire. Five pieces of glass are needed (Figure 4-2); one for the BOTTOM, two for each
       SIDE, and two for each END. The width of the END pieces will have to be narrower than
       the width of the BOTTOM  piece by two times the thickness of the SIDE pieces.  These
       specifications are necessary to assure that the ENDS and SIDES all fit inside the perimeter
       of the BOTTOM. Have the glass shop polish all the edges of the glass pieces on their
       machines so that they are smooth and square. Ask them not to bevel the polished edges.

2.     Purchase aquarium sealant from an aquarium supply shop.  Aquarium sealant is a high-
       quality glue for sticking pieces of glass together. Do not use ordinary silicone sealant for
       this - it  contains a compound that is  toxic to fish and  other animals. The tube will say
       "aquarium sealant" on it. Avoid contact between sealant and clothing.

3.     Squeeze a wide line of sealant out of the tube around the inside perimeter of the piece of
       glass to be used for the BOTTOM of the tank (Figure 4-2). Next,  prepare one END and
       one SIDE piece. Squeeze a line of sealant around the outside perimeter of 3 sides of the
       END piece. On the SIDE, squeeze a line of sealant along the outside edge of the bottom
       and just inside of the edge along each end.

                                   -Line of Sealant

Figure 4-2. Schematic of aquarium construction.
4.      Stand the END and SIDE pieces on top of the BOTTOM  piece.  Refer to  sealant
       instructions for guidance on how long support should be provided to newly bonded pieces.
       The edge of the SIDE piece should overlap the edge of the END piece at the corner as
       shown below.  Repeat this process with the other END and SIDE pieces.

5.      The tank will now be formed.  Make sure the ENDS and SIDES are square at the  corners
       and perpendicular to the BOTTOM. Remove excessive amounts of sealant. Leave the
       tank where it was assembled until the sealant dries.  It always stays somewhat rubbery.
       This drying process will take about 24 hours (refer to sealant instructions).

6.      After the tank has dried,  spread another line of sealant along all the interior seams of the
       tank  (i.e.,  where SIDES and ENDS meet and where  SIDES and ENDS meet the

7.      Fill your new tank with water to test that it is secure and leak proof.

       Safety note: Water is heavy! It  is never a good idea to try to carry even a small aquarium
       while it is filled with water.

                          Raising Algae and Water Fleas
                       (Adapted from Lacustrine Lessons, 1983)

       Overview:  This is a teacher preparation activity.

       Objective: To explain methods to raise and keep algae and water fleas (Daphnia) in the

       Materials:  Aquarium; air pump and tubing; air stone;  aquarium heater if the room is
       cool; large glass jars; gold fish; pond water; aged tap water.

       Preparation Time:  varies.

Teacher Instructions

A.     Background information:

       Daphnia (water fleas) are filter-feeding animals that consume algae.  They collect algae
on the fine setae (hairlike structures) of their filtering legs.  They can easily be kept alive in the
classroom or laboratory for extended periods of time as long as they receive an adequate supply
of fresh water and algae.

       The most  important considerations in keeping algal cultures healthy are to supply an
adequate amount of  nutrients and light, and to harvest the culture regularly so that it doesn't
become  overcrowded.  There are  many  complex methods described for maintaining pure,
bacteria-free, single-species cultures  of algae.  However,  Daphnia seem just as happy when
supplied with a mixed algal culture and may even benefit from the bacteria and the protozoans
that may be present.

       The following  culture method will allow you to keep both unicellular algae and Daphnia
alive with minimal effort.  Occasionally, a culture will crash (die off) for some unknown reason.  In
that case, you can get a new culture started from your nearest pond, biological supply house,
University, or EPA lab and try again.

B.     Algae Culture

1.     Set a five-gallon (or larger)  aquarium on a well-lighted window ledge,  or attach an
       aquarium light and timer set to give at least 10 hours of light each day. You will need a
       small air pump and air stone to keep the water circulating.  If the room drops below 68
       degrees Fahrenheit (F),  add an aquarium heater. The system works best  at 72-78
       degrees F.

2.     Fill the tank at least three-fourths full with hot tap water. Chlorine may harm your culture.
       If your water is chlorinated, or if you are not sure if it is or not, age the water by allowing
       it to sit for a day or two to allow the chlorine to vaporize.

3.      Start the algal culture by introducing an inoculum (starter set) into the tank. Sources of
       inoculum would be a few milliliters of very green water from someone else's algal culture
       or about a gallon of pond water.  Let the tank sit for a day or two so  that the algae can
       become established. Now add a few guppies or goldfish.  Feed the fish regular fish food
       daily. The fish provide nutrients for the algae (in the form of fecal material) and consume
       any zooplankton that may have been in the pond water.

4.      You should have a tank of greenish water in a week.  You should remove about one-fifth
       of the water each week or so and add aged tap or pond water so that the algae don't
       become over crowded.  If the water starts to clear up, add fresh inoculum, decrease the
       amount of water removed each week, or increase the amount of light  provided.

5.      The bottom of the tank should be siphoned  every three to four months (more often if you
       tend to overfeed the fish).

C.     Water Flea Culture

1.      Fill two  or three one-gallon (or larger) jars with tap water.  Large glass salad  dressing jars
       from restaurants work well. Let the water sit for a few days.

2.      Now add green water from the algal culture until the mixed water has a light green tint.
       Add a few water fleas (Daphnia) to each jar. Obtain them from someone else's culture, a
       supply  house, or collect plankton from a pond or lake using a fine mesh net.

3.      The animals should begin eating  the algae  and reproducing regularly. When the culture
       gets crowded, remove some of the water fleas to use for experiments or feed  them to your

4.      The water fleas may be captured using a fine-screened dip net.  Some may be injured if
       the dipping is too forceful. Both living and dead water fleas are excellent fish food.

5.      Water  fleas  may  also be captured alive by using a siphon tube to  capture  individual
       animals.  This technique  results  in fewer  injured  water fleas and is probably a better
       method for getting animals to use for experiments. Simply place a finger over one end of
       the siphon tube and put the open end of the tube near a water flea. When your finger is
       briefly lifted up, water and the water flea will be drawn into the tube.  Place your finger back
       over the tube and transfer the water flea to another container. A plastic pipet with a wide
       opening or a turkey baster will also work for transferring Daphnia.

6.      To keep your water flea culture healthy, add fresh algae to the jars about once a week.

7.      Every two or three weeks, the cultures should be thinned out to avoid over-crowding. To
       thin out the culture, you should pour half of the water flea culture into a clean, empty jar
       and fill it with aged tap water.  The remaining portion of the culture will include some dead
       animals along the bottom.  Use this part of the culture to feed your fish or just dispose of
       the animals.  Then rinse out the old culture jar and save it for the next thinning process.

8.      A final reminder:  these cultures do periodically "crash" (die), even for experts. Keeping
       two or  three culture jars going can help you avoid losing your whole water flea  supply.
       Never put the cultures in direct sunlight.



Environment on File. 1991. The Diagram Group, Facts on File, Inc., New York, N.Y. 10016.

Lacustrine Lessons.  1981.  Minnesota Seagrant Extension Program.  Duluth, MN 55812.

Lacustrine Lessons.  1984.  Minnesota Seagrant Extension Program, Duluth, MN 55812.

Project Stewardship Minnesota. State of Minnesota.  Environmental Education Advisory Board,
      St. Paul, MN 55155.

Project WILD - Aquatic.   1992.   Western Regional Environmental  Education Council, Inc.,
      Bethesda, MD, [Reprinted (or adopted) with permission from Project WILD].

                                    Appendix A
                                 Glossary of Terms

Bog:         A wetland where low oxygen  levels and soil temperature cause incomplete
             decomposition and limited drainage that results in an accumulation of fibrous peat.

Daphnia:     The genus of a large number of common species of small crustaceans commonly
             called water fleas.

Ecosystem:   An ecological community, together with its physical environment, considered as a

Environment: The sum of all external conditions and influences affecting the development and
             life of organisms.

Food Chain:   An arrangement of the organisms in an ecological community according to the
             order an organism consumes another organism in which each uses the  next
             (usually lowest)  member as a food source.

Fresh water:  Clean,  unpolluted water without salinity.

Groundwater: The supply of fresh water found beneath the earth's surface (usually in aquifers);
             often used to supply drinking water to wells and springs.

Nonpoint source
Pollution:     Pollution that cannot be traced to a specific origin or starting point, but seems to
             flow from many different sources.

Nymph:      An aquatic stage of development of some kinds of invertebrates.

pH:          A measure between 0  and 14 that indicates the relative acidity (pH less than  7) or
             alkalinity (pH greater than 7) of a substance.

Plankton:     Minute animal and plant life in a body of water.

Pollutants:    Solid,  liquid  or  gaseous substances that contaminate  the  local or  general

Predator:     An animal that eats another animal.

Prey:         An animal that is eaten by another animal.

Toxicity:      A response either immediate (acute)  or longer term (chronic) that changes an
             organism's ability to function normally.

Watershed:   A region or area that may contain several rivers, streams or lakes that ultimately
             drain to a particular watercourse or body of water.

Wetlands:     Land  or areas, such as tidal flats  or swamps, that  are often or periodically
             saturated with water.


                                   Appendix B
                              Additional Resources

Pond Life. 1987, by George K. Reid.  Golden Press, N.Y.

Wetlands. 1988, by William Niering. Alfred A. Knopf Publishers, Audubon Society Nature Guide


Earth Day Every Day.  1993, U.S. EPA Office of Water, Teacher's kit, Reference #EPA 800-B-93-

EPA Journal. Office of Communication and Public Affairs, Superintendent of Documents, GPO,
      Washington, DC 20402.

Hands On / Minds On:  Science Activities for Children. 1990,  American Indian Science and
      Engineering Society, 1085 14th Street, Suite 1506, Boulder, CO 80302-7309.

Science Activities, (magazine) Heldref Publications, 1319 18th Street NW,  Washington, DC
      20036. (1-800-365-9753).


WOW!: The Wonders of Wetlands. 1993, Environmental Concern, Inc., P.O. Box P, St. Michael,
      MD 21663. (410-745-9620).

                             SUPPLIES AND EQUIPMENT
Carolina Biological Supply, 1-800-334-5551.

Delta Education, 1-800-442-5444.

Sigma Chemical Co., 1-800-325-3010.

LaMotte Chemical  Products Co., P.O. Box 329, Chestertown, MD 2120.