Grade Level: 3-6

Subjects: Science, Art

Learning Standards: 3rd and 4th ECOLOGY

1. Describe a food web and the relationships within a given ecosystem.
2. Explain the difference between producers, consumers, and decomposers, with examples of each.

Goal: Students will understand the complexities and flow of energy in a food web, and the difference between a food web and food chain.

Time: 25 minutes for Web of Life; 35 minutes for food chain mobile creation.

Materials:

1. Pictures of marine organisms and sun (available here) – 1 per student – which can be made into signs to hang around one’s neck.
2. Ball of string or yarn
3. Supplies for food chain mobiles: unlined index cards, pipe cleaners, markers or crayons, hole punch, ribbon or string.

Introduction (5 min):

Have students seated in a circle, and together come up with the definition of an ecosystem (a biological community of interacting organisms and their physical environment.) We are studying the cold North Atlantic – the puffin’s ecosystem. Go around the circle and give each student a chance to name a living thing that shares the puffin’s ecosystem. Discuss how these organisms are connected by the flow of energy between them.

Group Activity (20 min):
Web of Life Activity 

The goal is to link everyone together using a ball of string. The string represents the transfer of energy from one organism to another.

Each student will receive a picture of a plant or algae to wear around their neck- their identity in the game. Ask each student to think about how their organism is connected to the others, in terms of “who eats who”. There is information printed on the back of each picture to help them (who I eat; who eats me).

The game begins with the sun (usually assigned to the teacher) who holds one end of the ball of string in one hand, and rolls it to someone with the other handThe person holding the ball of string will state their identity and then tell the others if they want to receive energy (by eating something) or give energy (by being eaten). They may read aloud the information about their animal or algae from the back of the card if they wish.

The sun is the only non-living thing in the circle, the source of all energy entering the ecosystem. The sun doesn’t need to eat anyone! But the only ones who can survive on the sun’s energy are the algae – phytoplankton and seaweed – who, like plants, can make their own food through photosynthesis. Algae and plants can grab the sun’s energy and bring it into the ecosystem for the animals.

Continue to pass the string ball until everyone is connected, and then marvel at the incredible web that has been created. The web includes everyone and is very strong due to all those connections. We can sense movements anywhere in the web, and reach anyone by following the lines of energy.

To add a measure of realistic vulnerability to this food web, you can pretend that there is an oil spill, or overfishing, an invasive species or disease….and then tell the students whose animals and plants would be most affected by this catastrophe to drop their part of the string. This can have a dramatic visual effect. Just a few lost players will weaken the whole web. Ask if this can really happen…. What are the lessons for us humans in this scenario?

Creative Activity (35 min):

After gaining an understanding of the complexity of a food web, it’s important to understand the difference between web (complex, multiple connections) and food chain (a straight flow of energy from sun to top predator). Students now have an opportunity to create their own food chain mobiles. Hold up an example of one that you made, or show them the picture of one here. Each student should write up a short plan of at least four organisms in their food chain, and must include the sun, and a “sun grabber” algae or plant. For example, the sun gives its energy to phytoplankton, the phytoplankton is eaten by zooplankton, the zooplankton is eaten by small fish, and the fish eaten by a puffin. Once you approve their plan as scientifically correct, give them blank index cards (you can pre-punch the holes top and bottom) to draw each “link” of the chain. Paper links may be joined by pipe cleaner links (1/2 a pipe cleaner per link) with a ribbon for hanging attached to the top link.