From Seed to Seed:
Plant Science for K-8 Educators

Activity 43: Ecosystem in a Jar

Grades: 5-8

Associated Lesson Topics:

• Ecology/Ecosystems

National Standards:

• SCIENCE: Standard C

Planting the Seed...

What makes up an ecosystem? Are all of the components of an ecosystem living? Are all of the components of the ecosystem independent or do they rely on one another? Is there a hierarchy, or are all components equal within an ecosystem? How many different ecosystems can you name?

Teacher Information:

If you are unable to schedule a field trip to visit a wetland, forest, or bog ecosystem (as we suggested in Activity 22: All Bogged Down), there is another option. You can create and investigate your own ecosystem in a bottle in the classroom. By collecting jars of pondwater, you and your students can explore a miniature ecosystem that is similar in its structure and function to much larger ecosystems.

In order to accurately represent the pond (or any) ecosystem, each jar should contain producers (algae and higher plants), consumers (tiny animals), and decomposers (bacteria and fungi). By observing the activities of and interactions among these organisms and their environment, students can document the cycles, changes over time, and diversity of the pond ecosystem.

Necessary Materials:

• Glass pint or quart jars with screwtop lids.
• Nails.
• Wax.
• Pond or lake water.
• Microscopes and magnifying glass.
• Crayons or colored pencils.

Procedure:

Denise Martin, a biologist and teacher education instructor in Burlington, Vermont, uses the following procedure to create pond ecosystems in a bottle:

• Provide each student with a glass jar.
• Use a nail to poke a hole in each lid and seal the hole with melted wax. This will act as a pressure-release valve when the organic matter in the jars creates gas buildup.
• Collect water from a pond or lake. Fill each jar 2/3 to 3/4 full with the pondwater and ½ to 1 ½ inches of mud from the bottom of the pond. You may also want to collect some visible producrs (algae and plants) and consumers (snails and insects).
• Before sealing the jars, have students make observations of the contents. Use magnifying glasses and microscopes, if available, to explore the pondwater. Suggest that the students also observe and use crayons or pencils to record the color of the water-or the amount of light passing through. The density of the green color is an indicator of the quantity of producers present, which will change over time.
• Place the jars on a windowsill.
• Although the jars should remain closed most of the time, students can occasionally open them to investigate the contents. They can remove a small amount of water and observe changes in the abundance of different organisms, color changes, and so on.
• We recommend continuing observations for six weeks, although under the right conditions, the ecosystems may remain healthy for months or years.

Harvesting the Crop...

Students can investigate how ecosystems respond to environmental changes by suggesting and testing simulations. Some suggestions follow.

1) 24 hours of light vs. natural (12 to 14 hours)

2) low pH (simulates acid rain) vs. actual pond pH

3) no light (cover with black paper)

4) addition of small quantities of fertilizer (simulates fertilizer runoff)

5) cold vs. warm temperature

6) addition of salt (simulates road salt runoff)

7) addition of commercial phosphate detergent (simulates pollution)

8) colored cellophane around jars (growth under different colors of light)

Sources

• Microscopes
  Carolina Biological Supply www.carolina.com

• Magnifying glasses
  Carolina Biological Supply www.carolina.com

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