Science Lesson Plan on the Forest Food Web

Introduce the lesson by asking students to brainstorm the different plants and animals that live in a forest ecosystem. They should come up with a variety of plants and animals, such as deciduous trees, evergreen trees, grass, flowering plants, mushrooms, deer, bears, mice, rabbits, squirrels, frogs, birds, foxes, hawks, snakes, insects, etc. Write their responses in a vertical list on the board or on chart paper.

Direct Instruction

Explain that each plant or animal in the ecosystem must obtain energy or nutrition in order to stay
alive. A food web describes the relationship between all of the organisms in an ecosystem, and how they obtain energy from one another. The three categories of organisms in a food web are producers, consumers and decomposers.

Producers get their energy directly from the sun by the process of photosynthesis. They are the basis of the food web. In the forest ecosystem, producers are trees, grass and other plants.

Primary consumers are herbivores such as rabbits, deer and some types of insects that feed exclusively on plants.

Secondary consumers are carnivores or omnivores that eat the primary consumers.

Tertiary consumers are larger predators such as coyotes, foxes and hawks that eat secondary consumers.

Decomposers such as fungi and bacteria feed on decaying plant and animal matter, breaking it down so that the nutrients can return to the soil.

Ask students to identify what role each of the organisms on the brainstormed list plays in the food web. Is it a producer, consumer or decomposer? Write their response in a second column next to the name of the organism. Then ask what each of the organisms on the list eats, and what animals eat it. For example, a rabbit eats plants, and it is eaten by hawks and foxes. Record the students' responses in a third and fourth column.

As a group, construct a diagram of a food web with all of the organisms they have identified. Draw the diagram of the food web on the board or chart paper. Leave the list visible so the students will be able to refer to it as they create the food web. Explain how all of the components in the food web are in balance, and if something happens to one of the components, it will affect all of the other components.

After completing the food web, choose various organisms in the food web and ask students what might happen if they were removed from the web. For example, if a predator such as a hawk or fox was removed, their prey could become overpopulated and there might not be enough food for them. On the other hand, if all of the rabbits were removed, the hawks and other predators would not have enough to eat.

Independent Practice

Students can make their own food webs by cutting pictures of plants and animals out of magazines, or drawing their own pictures.

Sources:

http://www.enchantedlearning.com/subjects/foodchain/
http://www.ucmp.berkeley.edu/exhibits/biomes/forests.php
http://www5.esc13.net/science/docs/manipulatives/simple%20forest%20food%20web.pdf