We are getting ready to do some baking later in the term, but first we needed to learn about how yeast works.  We mixed water, sugar and dried yeast. Some of the mixtures frothed up massively! But others didn't hardly even bubble. We thought about the water we put in - and we realised that the groups we did first had the warmest water and frothed the most. The ones we mixed last had cooler water. So what does this tell us about whether yeast needs heat?

We then left our experiments overnight: the mixtures had all collapsed - and our classes smelt like sour milk!