A simple food chain in a broadleaf forest is described. The giant panda is discussed as an example of an animal that relies on a single food source. It has now become endangered due to humans destroying its food source. A coastal food chain is used to exemplify how population changes are interconnected through food webs, but in theory are self-balancing.

The clip shows students how food chains can be combined to form food webs and also shows how different species are interconnected through feeding relationships. The class could choose a local ecosystem and construct a food web for it. Extend the activity to predict what would happen if an organism were removed from the ecosystem, or if a new species invaded.
Students could also model what would happen if numbers of an organism were to drop or rise significantly.