Fertilizer Frenzy

Summary: Students will design and conduct an experiment testing the effect of fertilizers/soaps on algae growth.

Category: Learning cycle / Experiment

Learning Objectives:

1. Students will design and conduct an experiment.
2. Students will evaluate other's experiments.
3. Students will describe relationships between biological systems and the environmental contaminants.
4. Students will work as a team to solve a problem.

• various samples of pond water (2 liter pop bottle avail. for ea. group)
• 5 to 7 different types of fertilizer / soaps (fertilizer should have different chemical ratios, soaps need to contain phosphate (look on ingredient label)
• clear glass or plastic containers (200 to 500 ml approx in size)
• microscopes/ slides/ cover slips/ droppers
• graduated cylinders
• balances
• available light source for algae growth (anything that could make a plant grow)

Sequence and duration of each part of lesson:

Exploration stage
Part 1 (90 minutes)

1. Place students in groups of 4-5.
2. Give 2 liter bottle of pond water to each group, and have them observe droplets under the microscopes. (Do not tell them about experiment yet.)
3. Have students make observations including a population count (some previous knowledge is helpful).
4. Ask students what do you use at home that might contaminate the pond water.
5. After brainstorming number 4, direct students attention to some common household contaminants (fertilizers / soaps), and ask students to predict the effect on pond water. Instruct students to design and conduct an experiment to test their prediction.
6. Instruct students to keep detailed lab notes. (Some instructions on how to keep good lab notes may be necessary.)
7. Have students set up experiments and place in the light. Make sure that they are labeled and protected from other students.
   Part 2 (15-20 minutes, 3 times a week for 3 weeks)
   • Students should be allowed class time to make observations-microscopes should be available.
   
   Part 3 (3rd week)
   1. Have students take final measurements and observations.
   2. Students analyze data and write conclusions.
   3. Have students clean up their entire experiment.

      Concept Invention
      Part 4 (30 min)

      1. This part of the lesson should be teacher directed discussion, where data and concepts are compared and developed.
      2. The teacher should start the discussion by asking, "What kind of relationships did you find?" The teacher should make sure that all groups report, and the findings are written on the board.
      3. The teacher should then ask, "What data do you have to support your findings?"
         • The teacher should write these by the conclusions from #2
         • A follow -up question to each should be, " Does anyone have data that would support or refute these findings?"
      4. The teacher could ask any of the following questions:
         • Do your findings support your hypothesis?
         • What do you like about each others experiments?
         • If you were to do this again, what would you change? Why?
         Application:
         Part 5 (15 min)
         • Give students a scenario, and have them write a half page paper on the scenario. For Example: "What effects would a dairy farm would have on a pond downstream?"

         Evaluation: There are multiple ways to assess this activity. Listed below are some possibilities:

         • Have students turn in Part 5 of the lesson, for teacher evaluation.
         • Have students evaluate their team members by giving them a score on team dynamics.
         • Have students exchange lab notebooks, and try to evaluate their experimental set up.

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         Copyright 1996. Utah State Office of Education, Curriculum Section, 250 East 500 South, Salt Lake City, Utah, 84111.

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