• During the guided practice, circulate around the classroom and check for students’ understanding of the roles of producers, consumers, and decomposers, and how energy flows through food chains.
• Check to ensure that the groups are listing organisms that are actually found in their assigned Pennsylvania ecosystems.
• Check the order of components in each group’s food chains.
• Collect and assess the Pennsylvania Food Chains worksheet.

Prior to the lesson, it may be helpful to locate books for students about various ecosystems in Pennsylvania, and plants and animals of Pennsylvania.

Tell students, “Today’s lesson is on ecosystems. Can anyone define ecosystem?” Accept all reasonable answers. “Can anyone give an example of an ecosystem you can find in Pennsylvania?” (Answers may include: forest, field, grassland, aquatic lentic/lotic, a city park.) “What ecosystems can we find in our school district?” (Answers will vary.)

Define community as all of the organisms that live in one area and depend on each other for survival. Ask students, “How is a community different than an ecosystem?” (An ecosystem includes nonliving things, too.) Have students write the definitions of community and ecosystem in their notes.

Write on the board: Food chains show a path of energy through an ecosystem. Write the following pattern for a food chain and have students write it in their notes:

Sun → producers → primary consumers → secondary consumers → tertiary consumers

Distinguish between producers and the three types of consumers in a food chain. Check for understanding by having students give you examples of each. Write an example food chain on the board, such as:

Sun → maple leaves → caterpillar → bluebird → garter snake → raccoon

Tell students that decomposers are bacteria and other organisms that break down dead producers and consumers into nutrients that return to the soil. Ask, “Where do decomposers fit on this food chain?” (Decomposers can fit anywhere, because they break down dead organisms at all of the levels.) “Why do we need decomposers?”

(We need them so they can add nutrients in the soil so that plants can grow.)

Ask students, “What is the source of energy for all of the organisms in the food chain?” (the Sun) “How do plants change the Sun’s energy?” (Through photosynthesis, they change the Sun’s energy into stored food energy, also known as chemical energy.) “What happens to the producers’ energy when consumers eat them?” (It is changed from chemical energy into energy for motion, also known as kinetic energy, and heat energy.)

Divide students into four or five groups, and give each group the Pennsylvania Food Chains worksheet (see S-5-5-1_PA Food Chains and KEY in the Resources folder). Assign each group a Pennsylvania ecosystem:

• Aquatic (lentic and lotic)
• Cornfield
• Forest
• City park
• Grasslands

Challenge each group to brainstorm as many plants and animals that live in their ecosystem as they can and write them on the worksheet. Ask them to be as specific as possible (e.g., oak tree instead of tree, robin instead of bird). Give them about 5 minutes to do so. If books on ecosystems are available, allow students to use them during this time.

When students are done with their list, give each group a green marker, a red marker, and a black marker, and have them circle producers in green, consumers in red, and decomposers in black. If they don’t have any decomposers listed, ask them to add one or two. Then have them follow the directions on the worksheet for making a food chain and answering the questions. Go over the answers to the questions with the entire class.

Food Chain Challenge

Give each group six 2" x 11" strips of paper and a glue stick. Have students choose a food chain from their ecosystem that includes the Sun; a producer; primary, secondary, and tertiary consumers; and a decomposer. Have students write one component of the food chain on each strip of paper, using the same color-coding system to show ecosystem roles. If time permits, they can add a picture of the organism. Then have them arrange the strips in order of energy flow, beginning with the Sun, and use the glue to form connected links in a chain. Note: Remind students that the decomposers can fit at any level of the food chain. Have each group present the name of its ecosystem and the food chain that students created. Display food chains in the classroom.

Who’s at the Top?

Tell students, “The name of this unit is Who’s on Top of Pennsylvania’s Food Chain? Did any of the groups have the same consumer at the top of their food chains? How should we judge who is at the top?” Hold a short discussion on the question; there is no right answer.

Extension:

• For students who might need opportunities for additional learning, provide the names of organisms in the ecosystem and have students classify them as producers, consumers, and decomposers. To reinforce concepts, provide additional examples of food chains for various Pennsylvania ecosystems and have students explain how energy is transferred as it travels through the food chain.
• Students who need extra practice with vocabulary can complete the Ecosystem Matching worksheet (see S-5-5-1_Ecosystem Matching and KEY in the Resources folder).
• Students who might be going beyond the standards can refer to an energy pyramid, such as the one below, and explain how it models energy transfer in a food chain. Challenge them to answer the question, Why are there more producers than consumers in a food chain? (Because energy is lost at each trophic level, as heat and kinetic energy. The consumers must eat more producers to have enough energy.)