Microorganisms are helpful in the disposal of human waste. Our waste material in the form of sewage is treated at a sewage farm. The clean and filtered water is finally sprayed over rocks and any microscopic bits of sewage still remaining are eaten by a variety of microorganisms. There is a beautiful and fascinating sequence of magnified microorganisms. The clean water is then fit to be released into a river.

This clip is from:
Science Clips, Micro Organisms
First broadcast:
11 October 2007

Useful when looking at microorganisms and how beneficial microbes work. You could show the clip and then invite the children to investigate sewage treatment and the whole cleaning process of water contaminated with human waste, step by step. Perhaps ask the children to make two fact lists about microorganisms - one marked with a frowning face listing all the 'bad' work they are doing and one with a smiling face listing all their beneficial properties.
You could stop the clip showing a microorganism and ask the children to make a drawing of it in as much detail as possible. After that you could ask them to try to identify their 'head' or 'mouth' and think about the 'body parts' of a microorganism.