Sitting in a circle version:
Sit at the carpet in a circle.
Hand each student a card with a living thing on it. Students hang it around their neck to display their living thing for everyone to see. Each student takes a turn to tell the class what living thing they are.
Tell students that energy comes into the living things from the sun, and ask which living things use the energy of the sun to stay alive. [Any plant]
For the chosen plant, start the yarn at that student: tape the end of the yarn to the carpet with duct tape in front of them. Ask this student to take off their living things label and place it on the duct tape in front of them.
Using students' ideas, unwind the yarn ball to a student that has a living thing that would eat the plant. Make a line of wool stretching between them, then tape the yarn strand to the floor in front of the new living thing.
Continue, connecting more living things together with yarn (it will criss-cross). Each time a student is added to the line of yarn, ask them to take off their label and place it on the duct tape, so you can see who has not been included yet.
Once you get to the top of the food chain (top predator, like cougar), you can move back down the food chain to something that is eaten by the predator. Move up and down the food chain as needed to connect everyone. At any point, you can connect to decomposers (slug, wood bug, mushroom) as they eat or grow out of a living thing after it dies. The order does not matter, but just connect all the living things to something else by who eats who.
A criss-crossing web of connections is made, forming a 'Food web'. (A food web is many connected food chains.)
For younger students, include each student once, then discuss how there are many more connections.
For older students that can sit longer, each living thing could be connected more than once.
Once the web is done, ask students to look at the web shape they have made with the yarn. This is why it is called a food web.
I also ask students to point to one other living thing that they are connected to in addition to the ones they are linked to by yarn. We have only made a part of the food web with the wool - there are many many other connections.
Discuss why biodiversity is important. If one living thing dies off, living things connected to it can find other things to eat because there are so many connections. With less biodiversity and fewer kinds of living things there are less back-ups in the system, so it is not as resilient.
For clean up, ask students to hand in their labels, then they should peel up the duct tape without moving the yarn. The yarn can then be wound back up backwards along its path without getting tangled.
This activity is inspired by: https://betterlesson.com/lesson/640194/the-food-web (see the Explore/Explain section).
Tabletop version:
Give student groups a stack of index cards with a living thing named on each.
Students lay the cards on a table, then use lengths of wool to connect the living things that eat each other.
Students could add their own living things to their food web.
Compare the food webs that each group made.
As a class, discuss how complicated a food web is, and how living things depend on each other. If one living thing is removed, through habitat change or human interference, other living things are affected.
