Student Experience 4: What do decomposers do?

Purpose

To help students understand that decomposers recycle nutrients in an ecosystem.

Description

Students have seen images of decomposers leading to the rotting of various foods and helping to make compost. Begin by asking students for their thoughts about decomposers’ role in the ecosystem. After discussing their ideas, watch the following videos.

NOVA: Decomposers
https://unctv.pbslearningmedia.org/resource/tdc02.sci.life.oate.decompose/decomposers/#.WXC4dIQrKCh

Crash Course Kids: The Dirt on Decomposers
https://www.youtube.com/watch?v=uB61rfeeAsM

After showing students the two videos, lead a discussion using the Questions to Ask Students about the importance of decomposers.

Questions to Ask Students

What do decomposers consume?
- What do decomposers do with the energy they get from consuming?
What role do decomposers play in the ecosystem?
- What might happen if there were no decomposers?

Science Practices

Constructing Explanations When asking students to consider what might happen if there were no decomposers, prompt students to predict what other organisms may be affected and to provide evidence to support their predictions.

Student Thinking

Students tend to think that decomposers and decomposition is gross; this experience is intended to help them understand that decomposers not only cause things to rot—they play an important role in the ecosystem of recycling nutrients.

Implementation Tip

In the post-video discussion, it is important that students talk about how decomposers return nutrients from dead things and organic waste material back to the soil and air, creating a nutrient-rich environment for plants to grow.