Science/Strand III/Content Standard 5/Middle School/Benchmark 3
Benchmark Question: How is energy distributed to living
things in an ecosystem?
Focus Question: How does a change in one population
affect the other organisms in a food web?
Students should envision a
Michigan forest and describe the populations living in a natural balance.
They should brainstorm a list of the different organisms that live there:
1. Plants: beech trees, maple trees, raspberry bushes,
dogwood trees, moss, trillium
2. Animals: robins, white-tailed deer, squirrels, owls,
mice, garter snakes, earthworms
3. Other: fungus, bacteria, lichens
Each student will construct
a food chain:
1. Write the names of organisms on index cards
2. Punch a hole at the top of each card
3. Use yarn to show how organisms are connected in a
4. Share his or her food chain with the group
In small groups, students
will share their food chains to construct a food web and present their webs
to the class. As a class, evaluate each group’s web to make sure they
formed a food web and not just a food chain.
The teacher will present the
following scenario to the class:
A camper is careless and leaves his or her site with
a campfire burning. A spark ignites the dry grass due to drought conditions.
This fire is stopped, but not before it wipes out the mouse population.
Predict the changes that will occur in the other populations within the
forest food web.
After reading the scenario,
each student will remove the “mice” card from their webs. As a class,
discuss which populations within the web may increase or decrease after the
removal of the mice population from this ecosystem.