Lesson 3 — Food Webs, Decomposers and a Changing Ecosystem

Biological sciences. Students connect several food chains into a food web using a string-web modelling activity, and discover that having more than one food source makes an ecosystem more resilient to change. They investigate decomposers through a fruit-decomposition time-lapse, learning that decomposers break down dead plants and animals and return nutrients to the soil, which producers use to grow \u2014 so every living thing in a web has arrows leading back to a decomposer. Students distinguish indigenous from introduced Western Australian species (numbats, quenda, bobtails vs cats, foxes, rabbits, cane toads) and trace how an introduced species or a broken link affects the whole web. Includes a slide deck with an animated food web forming and nutrients cycling, the Food Webs and Decomposers worksheet, and the Indigenous and Introduced Species card resource. Connects strongly to Sustainability and to Aboriginal and Torres Strait Islander histories and cultures.