Grade: Grade 3
Subjects: Language arts, visual arts, science
Duration: One hour
Setting: Indoor, classroom
Students will investigate the food web of living organisms in a lake community by reading a story and constructing a mobile or mural.
Students will be able to:
1. show how aquatic animals are interconnected by their feeding relationships;
2. explain the similarities and differences between food chains and food webs; and
3. use chains or webs to describe the interrelationships of at least three members of a lake community.
Class set of Student Sheets 1 and 2; newsprint; construction materials for mobiles or murals (e.g., hangers, paper plates, string, construction paper, scissors and crayons)
In the story, “If I Were a Fish” (see Student Sheet 1), a simple set of interactions is developed. The key components of the lake community and their connections are outlined on Student Sheet 2. The diagram shows that members of an aquatic community depend on other members of that system for food. A series of dependent relationships forms a food chain. A food chain is an ordered list of who eats whom. When several food chains are linked together, they form a food web. In any community, all living organisms are linked together by a “what they eat” and “who eats them” relationship.
Aquatic insects spend part or all of their lives in water. Familiar aquatic insects are midge fly larvae, mayflies, dragonflies, water boatmen and giant water bugs. Some of these insects eat plants, phytoplankton, decaying plant and animal matter, zooplankton and molluscs.
Small drifting aquatic organisms in the water are called plankton. There are two kinds of plankton: phytoplankton and zooplankton. Phytoplankton are little aquatic plants that photosynthesize (produce food using carbon dioxide, water and sunlight). Some examples of phytoplankton include blue-green algae and diatoms. They form the base of most food chains in lakes. Zooplankton are microscopic aquatic protozoa, crustaceans and other animals with names like amoeba, paramecium, amphipod and fairy shrimps. These animals feed on phytoplankton, bacteria, or decaying plant and animal matter.
Molluscs have a soft body that is often enclosed in a shell. Familiar molluscs are snails and mussels. These animals tend to feed on phytoplankton, zooplankton, and decaying plant and animal matter.
1. Have one student read aloud the story “If I Were a Fish” on Student Sheet 1.
2. Have students identify all living things in the story. Draw as many food chains as possible. Then have students incorporate the food chains into a food web. You may wish to use the food web diagram on Student Sheet 2.
3. Have students design a mural or mobile to represent the food web. Organisms may be designed with rolled strips of construction or tissue paper to create a threedimensional effect.
1. Given any one organism, see how many direct and indirect connections the students can make to other living and non-living things in the lake.
2. Play the following “linking” game: The first student is given the name (or a picture) of one lake organism. He or she must name a living or non-living thing that the organism is directly linked to and describe the linkage. The next student must make a direct link starting with the thing named by the first student and so on. Things may only be named once.
1. Have students act out the interactions that take place in the community. Students may make costumes with garbage bags and construction paper to develop an identity.
2. Have students observe and/or research one of the living organisms in the story and write an article that could be published in a school or nature magazine.
3. Have students develop a food web for a different aquatic community, such as for a river, wetland, brackish or saltwater community.
Adapted from the Fish Ways Activity Guide, with permission from the Canadian
Wildlife Federation and the Ontario Ministry of Natural Resources.
(For more information about the availability of the Fish Ways Activity Guide and how
to enrol in Fish Ways workshops, see www.WildEducation.org.)