This is all explained very nicely in a boingboing blog post called Yeast? Where We’re Going, We Don’t Need Yeast. And – a warning – there’s not so nice picture of fermenting yeast! To learn even more about it read this page on Exploratorium.

Yeast is just fascinating on a lot of levels. And a yeast science project is almost too easy to do. You can usually get anything you need at the supermarket and results are almost instantaneous. The fermentation of yeast is a chemical change, and there are tons of different demonstrations and experiments that you can use for your science fair.

Our The Yeast Beast project, for example, is advertised as a demonstration, but it can also be done as a science experiment, and instructions for doing it that way are in the guide.