Hands-on Activity: Got Energy? Spinning a Food Web
Educational Standards :
Learning Objectives (Return to Contents)
After this lesson, students should be able to:
Materials List (Return to Contents)
Each group needs:
For the entire class to share:
Introduction/Motivation (Return to Contents)
In your own words, can you explain what makes an environment or an ecosystem? (Key points: An environment is the surrounding area that an organism lives in, including the air, water, food and energy for that organism to survive. An ecosystem is a whole working unit that includes an area's living organisms and nonliving environmental conditions, linked by nutrient and energy cycles.) How is the environment you live in different from another animal's, say a frog or a deer? How are these environments the same? (Make a T-chart on the board or overhead projector to list environment similarities and differences.) What keeps an environment in motion? What fuels the animals and plants that live within these ecosystems? That's right, nutrients, water and energy!
Why do we eat breakfast, lunch, dinner (and maybe a snack) every day? We must eat to provide ourselves with the nutrients that help us to move, grow and stay healthy. Our food gives us the energy we need to perform daily activities. Do you know what is in food that gives us energy? (Answer: Nutrients, including proteins, carbohydrates and amino acids.)
Who remembers what a food chain is? A food chain is a series of nutrients and energy moving through a chain of organisms. Can you trace a food chain of the vegetables, fruit, cheese, eggs or meat that you had for breakfast or will have for dinner? Who can give us an example of a food chain? (Examples: Sun --> grass --> cows [hamburger, milk, butter, cheese], Sun --> soybeans [tofu, soymilk], and Sun --> wheat plants --> wheat grain [bread].) Where do all of these food chains start? That's right, the sun! All food chains start with the sun, which provides energy to producers (organisms that are capable of making their own food, such as plants) that use photosynthesis to grow and become food for consumers like us (any organism that gets its food by eating producers or other organisms). Decomposers (such as bacteria, molds, mushrooms and mildew) break down discarded plant and animal (organic) materials into simpler substances, which returns nutrients to the soil and atmosphere for new plants to use to grow.
Now, why would an engineer care about a food chain? Well, because engineers are interested in everything that involves energy. It is the job of engineers to come up with new fuels and ways to conserve the energy we already use. Many types of engineers — chemical, mechanical and civil — work on projects that use energy flow and transfer. Energy efficiency (saving energy) and energy sources are incredibly important fields as everyone wants to find ways to use fewer natural resources, such as trees and fossil fuels, as energy sources. Can you name any renewable energy sources? (Examples: Wind, water and solar.) Engineers also investigate foods and how they grow and supply us with energy. Engineers look at how energy moves through a food chain and use that understanding to develop other energy technologies, even biodomes and space stations. Engineers ask questions such as, "How much energy is needed to grow plants in this environment?" and "How much food is needed to provide enough energy to the organisms or people living in this environment?" Those are some pretty important questions!
Today, we are going to learn more about food chains and a special type of food chain called a food web. Can anyone guess what a food web is? A food web is what happens when one organism gets energy from more than one source, such as people eating vegetables, chicken and milk for one meal. Food chains are often drawn with arrows that point in one direction, for example, from the sun to a plant. The arrows show us the direction that energy is moving through a food chain. Food webs are more complicated; they have arrows that go all over the place, from animals to both plants and other animals. Are you ready to look at some food webs? Let's go!
(Optional: This may be a good time to use the attached Example Food Web Worksheet to acquaint students with the concept of food webs before beginning the activity.)
Vocabulary/Definitions (Return to Contents)
Procedure (Return to Contents)
Before the Activity
With the Students: Part 1 — Human Food Web
With the Students: Part 2 — Drawing Food Chains and Webs
Troubleshooting Tips (Return to Contents)
It may help to do an example food chain and/or web on the classroom board to clear up confusion before gluing begins. Or, use the attached Example Food Web Worksheet to acquaint students with the concept before beginning the activity.
Assessment (Return to Contents)
Idea Web: Ask students to brainstorm a list of environments. What different organisms live in these environments, both plants and animals? From where do these organisms get their energy and nutrients? Are there any energy or nutrient sources that are the same for all the environments?
Activity Embedded Assessment
Hypothesize: Ask each group what would happen if we combined two or more of their food webs. (Answer: If the food webs were combined, they would become more complex. More consumer food options might result. Fewer energy sources [plants or producers] might lead to more competition for food among the consumers.)
Drawing: Have students draw a diagram of their food web in the Part 1: Human Food Web activity.
Informal Discussion: What Happens to the Energy? Solicit, integrate and summarize student responses.
Activity Extensions (Return to Contents)
Add-on to the Part 1: Human Food Web. Have one species in the web suddenly be threatened by extinction by asking that student to sit down. Which student(s) feel a tug on their string as a result of the first student sitting down? Those students should also sit down, and so on. Every student should end up sitting, since they are all connected. Make sure that one of the species in the web is a human; this helps to illustrate the human impact on other living things. (Adapted from: the Cornwall Wildlife Trust's Education Center, http://www.cornwallwildlifetrust.org.uk/education/school_grounds_activities).
Alternate project for Part 2: Drawing Food Chains and Webs. If string and wire or straws are available, have students construct their food webs as mobiles.
Assign students to research food webs in a variety of ecosystems online or in natural history books. Omnivores, such as humans, bears and skunks, often have more complicated food webs.
Activity Scaling (Return to Contents)
References (Return to Contents)
Bush, Mark B. Ecology of a Changing Planet, Second Edition. Saddle River, NJ: Prentice Hall, 2000.
Dictionary.com. Lexico Publishing Group, LLC. Accessed December 5, 2006.
Food Chains and Webs, Making a Food Chain. Cornwall Wildlife Trust, UK. http://www.cornwallwildlifetrust.org.uk/ Accessed December 5, 2006. (Source of part of this activity; also includes additional fun and easy classroom and student activities)
ContributorsChristopher Valenti, Malinda Schaefer Zarske, Denise Carlson
Copyright© 2004 by Regents of the University of Colorado.
Supporting Program (Return to Contents)Integrated Teaching and Learning Program, College of Engineering, University of Colorado Boulder
Acknowledgements (Return to Contents)
The contents of this digital library curriculum were developed under a grant from the Fund for the Improvement of Postsecondary Education (FIPSE), U.S. Department of Education and National Science Foundation GK-12 grant no. 0338326. However, these contents do not necessarily represent the policies of the Department of Education or National Science Foundation, and you should not assume endorsement by the federal government.