877-542-5504 877-542-5504

Want to Help Fellow Teachers?

Please help us grow this free resource by submitting your favorite lesson plans.

Lesson Plan #:AELP-ECL001
Submitted by: Jess Lang
Endorsed by: Dr. Don Descy Date: February 1997

Grade Level(s): 4, 5, 6, 7, 8


  • Science/Ecology

Description: Students will construct an aquatic ecosystem in a two-liter pop bottle. The stock organisms will be: water plants, snails, and fish. Students will record data concerning the observations they make over a four-week period.

Goal: Students will exercise important early scientific skills, like observing, measuring, classifying, communicating data, inferring, and predicting.


  • Students will, in groups of four, construct aquatic habitats in pop bottles.
  • Students will create charts to record data from observations.
  • Students will observe the habitats over a period of four weeks, and record what they see–changes in population, plant growth, water quality, and animal growth.
  • At the end of the observation period, students will graph their data.
  • Students will write explanations for what they observe. Also, questions will be posed with specific questions, such as: What would happen to your plant population if you added more snails? or What environmental factors do you think influenced the growth of your fish/snails/plants? or What do you think would happen if the fish population doubled? Quadrupled?
  • Materials:

  • 2 two-liter pop bottles for each group
  • water source
  • light source
  • guppies
  • elodea
  • duckweed
  • water snails
  • sand
  • scissors
  • graph paper
  • Procedure:

  • Cut the top off one bottle, at the shoulder (where it tapers). Cut the base off another bottle and score it with holes. This is the cover.
  • Fill bottom of bottle with sand, two inches deep.
  • Add water–slowly, to minimize sand displacement–and then root three ten-centimeter elodea stalks firmly in the sand. Sprinkle a small amount of duckweed onto the water’s surface.
  • Let the aquaria stand overnight to let the sand settle, and to allow chlorine from water to dissipate (if tap water is used).
  • Add two guppies and two snails.
  • Over a four-week period, have the students record daily observations in journals. Suggest certain things for them to be watching for, like plant growth or population changes. Ask for quantitative measurements (exactly how many? exactly what size? how many days?) as well as qualitative (what color? what shape? slow or quick movement?). During the observation period, have students research pond ecology and the organisms involved in the project.

    At the end of the observation period, have the students graph the information they’ve obtained through observation. At this time, they should write hypotheses to explain some of the things they’ve seen.


    Are the aquaria appropriately stocked? Have they been well-maintained? Are observations recorded at regular intervals? Are graphs drawn correctly? Are hypotheses based in fact?

    Useful Reference:
    Information about bottle aquaria taken from Bottle Biology, copyright 1993, by the Bottle Biology Project, University of Wisconsin–Madison.