South Carolina ETV

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Columbia, SC 29201-4761
Phone: 803-737-3545

Oh, What a Tangled Web We Weave! (Grade 5)

Master Teacher

Lori Givens

Time Allotment

Two to three 40-minute class periods

Overview

It is often said that "Humans are at the top of the food chain." What is meant by this? How does a food chain differ from a food web? These questions and more will be answered in this lesson. This lesson explores food webs and the different components of food webs through video clips and Web sites.

Subject Matter

Life Science

Learning Objectives

Students will be able to:

Describe the difference between a food chain and a food web.
Explain the roles of a decomposer, producer, and consumer in a food web.
Diagram the flow of energy through a food web.
Explain what happens to the amount of energy as it flows from organism to organism in a food web.

South Carolina Curriculum Standards

(These Standards are available online at http://www.myscschools.com/offices/cso )

II. Life Science

Units of Study: Cells and Systems and Ecosystems (Aquatic/Terrestrial)

1. Populations and Ecosystems

2. Populations of organisms can be categorized by the function they serve in an ecosystem. Plants and some microorganisms are producers-they make their own food. All animals, including humans, are consumers, which obtain food by eating other organisms. Decomposers, primarily bacteria and fungi, are consumers that use waste materials and dead organisms for food.

a. Distinguish among the roles organisms serve in a food web (producers, decomposers, consumers, prey and predators).

3. For ecosystems, the major source of energy is sunlight. Energy entering ecosystems as sunlight is used by producers through photosynthesis.

a. Recognize that energy passes from organism to organism in food webs.

b. Diagram how energy flows through food webs.

Media Components

Video

Food Chains and Webs

"Food Chains and Food Webs" (1:53) This clip distinguishes between food chains and food webs. It shows examples of both and states why food webs are more realistic than food chains. This clip also introduces herbivores, carnivores, and omnivores.

"Decomposer" (:54) This clip focuses on the importance of decomposers in food webs. Decomposers recycle nutrients from dead organisms to allow new organisms to flourish.

Biology: The Science of Life: Ecology: Organisms in Their Environment

"Pyramids of Energy and Numbers: Consumer Levels" (1:55) This clip examines the flow of energy through the food chain. ( Note to Teacher: You will use only 50 seconds from this clip.)

To access these video clips, log on to your account at ETV's StreamlineSC Web page ( http://etv.streamlinesc.org ). In the search by keyword box, type in the series title Food Chains and Webs or Biology: The Science of Life: Ecology: Organisms in Their Environment and hit go. Click the series title and then click the video segment you want and download it to your desktop.

(Note to Teacher: If you don't have an account with ETV's StreamlineSC , check with your media specialist about signing up for an account.)

Web Sites

Food Chains and Webs

http://www.vtaide.com/png/foodchains.htm

This Web site discusses both food webs and food chains. There are examples of each type on the Web site. This site also provides students with the opportunity to create their own food web using the pictures of animals the site provides.

Food Webs

http://www.gould.edu.au/foodwebs/kids_web.htm

This interactive Web site focuses on food webs from four different ecosystems: African Grasslands, Australian Grasslands, Antarctic, and Marine. Students place the producer or consumer in the correct place in the food web. Each of the four food webs are different in that one food web may classify decomposers and scavengers along with the producers and consumers while another food web may classify herbivores and carnivores along with first and second level consumers.

Fun with Food Webs

http://www.harcourtschool.com/activity/food/food_menu.html

This interactive Web site focuses on meadow, arctic, and pond food webs. Students drag the producer or consumer to the correct place in the food web.

Materials

Per Class:

Pass the Energy, Please! by Barbara Shaw McKinney (Dawn, 2000)

(Note to Teacher: Prepare transparencies of the picture book if using an overhead instead of an ELMO.)

Per Student:

Science notebook

Equipment

Computer with Internet access to share video from ETV's StreamlineSC
LCD Projector
Computer lab so each student can manipulate the Web sites
Overhead or ELMO

Prep for Teachers

Set up your free ETV StreamlineSC account so you will have access to all United Streaming videos. Check with your media center or technology specialist for a passcode if you have never used StreamlineSC .
Download the video clips listed under Media Components from StreamlineSC to your desktop.
Bookmark the list of Web sites.
Load the following plug-ins: Media Player or Quick Time, Java, and Flash. You will also need Internet Explorer 4 or higher to view one of the Web sites.
When using media, provide students with a Focus for Media Interaction , a specific task to complete and/or information to identify during or after viewing of video segments, Web sites, or other multimedia elements.

Introductory Activity

Step 1: Ask your students:

"How do you get energy to complete your daily activities? (Possible answers include: from the food you eat, vitamins, etc.) Where does the energy come from?" (the nutrients in the food we eat)

"Where do animals get their energy?" (nutrients in the food they eat)

"Where do plants get their energy? (The sun gives them energy which enables them to produce their own food through photosynthesis.)

"Think about what you ate for supper last night. Could you illustrate a food chain based on what you ate? (Accept answers.)

Step 2: ( Note to Teacher: This lesson is targeted as a fifth grade lesson. Students are introduced to food chains in third grade; so the following steps serve as a review of food chains before students are asked to compare food chains and food webs.)

Pass the Energy, Please! is a book that focuses on food chains from different habitats. Each section in the book adds an extra link to the food chain. Place the book on the ELMO or the transparencies on the overhead so students can see the pictures as you read. Provide students with a Focus for Media Interaction by asking them to listen to how a plant produces its own energy. (Combining carbon dioxide, water, and sunlight in the process of photosynthesis, it makes its own food.)

Step 3: BEGIN reading pages 4-7 entitled "Link Number One-Born in the Sun." PAUSE after reading page 7. Ask the students the Focus for Media Interaction question again to check for comprehension.

Step 4: Provide students with a Focus for Media Interaction by asking them to listen for how energy is transferred through the food chain. BEGIN reading pages 8-9 entitled "Chains of Two-The Big Herbivore Crew." PAUSE after reading page 9 and ask students how energy was passed from the grass to the herbivores. ( The grass produced its energy through photosynthesis and the herbivore received energy from the grass it ate.)

Step 5: Ask students to infer from the reading what a carnivore is. (A carnivore is an animal that eats only meat.)

Step 6: Provide students with a Focus for Media Interaction by asking them to draw the food chain in their science notebooks as you read. BEGIN reading pages 10-11 entitled "Three in a Chain on the African Plain." PAUSE after reading page 11. Ask the students what the food chain for the African Plain looks like. (grass Þ gazelles Þ cheetah) Ask the students to infer what carnivorous means. (It describes an animal that eats meat.)

Step 7: Provide students with a Focus for Media Interaction by asking them to draw the food chain in their science notebooks as you read. BEGIN reading pages 12-15 entitled "A Chain of Four on the Meadow Floor." PAUSE after reading page 15. Ask the students to identify the links in the food chain. (milkweed pod Þ mouse Þ snake Þ owl)

Step 8: Provide students with a Focus for Media Interaction by asking them to draw the food chain in their science notebooks as you read. BEGIN reading pages 16-19 entitled "Arctic Five Link Up To Survive." PAUSE after reading page 19. Ask the students to identify the links in the food chain. ( Phytoplankton Þ zooplankton Þ anchovy Þ Arctic seal Þ polar bear)

Step 9: Provide students with a Focus for Media Interaction by asking them to draw the food chain in their science notebooks as you read. BEGIN reading pages 20-23. PAUSE after reading page 23. Ask the students to identify the links in the food chain. (goldenrod Þ caterpillar Þ spider Þ warbler Þ weasel Þ red fox)

Step 10: Provide students with a Focus for Media Interaction , by asking them to develop their own definitions of a scavenger and a decomposer and to give examples of each. BEGIN reading pages 24-30. PAUSE after reading page 30 and ask students, "What is a scavenger?" "What is a decomposer? What are examples of each?"

Step 11: Conclude by asking the students, "How is a food chain significant to the survival of all animals?" (Interdependence within the food chain helps to keep the plant and animal populations balanced. For example: If there are not enough milkweed pods, the mice will not have enough to eat, so the mice population will decrease. Because the mice population decreases, so does the snake population and eventually the owl population.)

Learning Activity

Step 1: The book we just read focused on food chains. We are now going to watch a video clip on food webs. Do you think there is a difference between food webs and food chains? If so, what is the difference? (Accept student responses.) Instruct students to write responses in their science notebooks.

Step 2: Provide students with a Focus for Media Interaction by asking students, "When we eat something what are we taking in?" (matter and energy)

Step 3: BEGIN the video clip entitled "Food Chains and Food Webs." PAUSE the video on the screen that shows a food chain labeled "Decreasing Energy." This screen immediately follows runners in a race and the statement, "We need energy to move and carry out body functions." The time on Media Player reads :20.

Step 4: When the food chain is paused on the screen, discuss the Focus for Media Interaction and then ask them to identify what is being eaten by what and how the energy is being transferred. (Nymph is eating the phytoplankton, the trout is eating the nymph, and the heron is eating the trout. The phytoplankton produces its own energy. Energy decreases as it flows through the food web.)

S t ep 5: After the discussion, provide students with a Focus for Media Interaction by asking them to distinguish between a food chain and a food web. Click PLAY on the computer screen.

Step 6: PAUSE the video on the screen with the Food Web. You will hear: "As you can see our food chain quickly becomes a tangled web." The time on Media Player will read 1:40. The answer to the following question should be written in the students' science notebooks. Ask students to distinguish between a food chain and a food web. Students can share their thoughts when they finish recording their answers.

Step 7: Give students a Focus for Media Interaction by asking them to listen to the video and compare their answers to the information in the video clip. PLAY the video. Compare the food chain and the food web together as a class.

Step 8: Ask students: "Use the information from Pass the Energy, Please! and the video to write in your science notebooks the definition of a carnivore, omnivore, and herbivore. Allow students to share out the information in a small group or to the whole class. (carnivore: animal that eats only meat, omnivore: animal that eats meat and plants, herbivore: animal that eats only plants)

Step 9: We are going to watch another short video clip. Provide students with a Focus for Media Interaction by asking them what happens to an energy level as it is passed from organism to organism. Students should record their ideas in their science notebooks and then share out. (Accept all answers.)

Step 10: BEGIN the video clip entitled "Pyramids of Energy and Numbers: Consumer Levels."

Step 11: STOP the video after hearing the phrase, "Only 5 % of the available energy is passed on" and seeing a pyramid with the words "5% of the energy is passed on." The time on Media Player will read 1:05. Ask students what happens to the energy level in the food web as it is passed from organism to organism. (It decreases.) ( Note to Teacher: You will not view the remainder of this clip.)

Step 12: Tell students that there is one more important factor in a food web: a decomposer. Ask students to recall what a decomposer is based on the reading of Pass the Energy, Please! Students should record thoughts in their science notebooks. Provide students with a Focus for Media Interaction by asking students how a decomposer is a vital component to a food web. (Decomposers recycle nutrients from dead organisms allowing living ones to flourish.)

Step 13: PLAY the video clip entitled "Decomposers" from the StreamlineSC series Food Chains and Webs .

Step 14: Discuss with students the importance of decomposers in a food web.

Step 15: Tell the students: "We are now going to take the information you have gained from the video clips and the read-aloud to participate in food web simulations online." Allow students to access http://www.gould.edu.au/foodwebs/kids_web.htm . Provide a Focus for Media Interaction by instructing students to access each of the four food webs and to follow their instructions. When students have completed a food web, they should click on the link that says, "Click here to view the completed food web."

Step 16: Check for Understanding by viewing the students' completed food webs on the computer. You can also accomplish this by having partners compare their food webs and check each other's webs for correctness.

Step 17: When students have successfully completed all four food web simulations and have viewed the food web diagrams, they may access the following Web site:

http://www.harcourtschool.com/activity/food/food_menu.html. Provide a Focus for Media Interaction by asking students to draw each of the completed food webs when they have completed them. They should have three complete food webs.

Step 18: Check for Understanding by checking over the students' drawings of the three different food webs.

Culminating Activity

Step 1: Tell students: "Now that we have read a book, watched three video clips, and completed food webs on the computer, you are going to create your own food web online. Access http://www.vtaide.com/png/foodchains.htm. Click on "Creating a Possible Food Web," which is located about halfway down the page. Follow the directions."

( Note to Teacher: You may want to give students a set number of organisms they must use in their food web.) When they have completed their food webs, have students print them out.)

Step 2: Once their food web is printed out, students should label decomposers, scavengers, consumers and, producers. Check their webs for comprehension.

Cross-Curricular Extensions

Art: Students can make a mural of a food web. Allow students to make a food web of their school's mascot or their favorite team's mascot.

Community Connections

Bring in a presenter from DHEC to discuss the effects of pollution, etc., on a food web.