Year 5 are studying micro-organisms in Science lessons. We have been investigating yeast, a tiny living thing that can do amazing things. We have conducted some experiments. Firstly we wanted to know what yeast needs to ‘work’ best. We set up an experiment with 4 bottles. Bottle 1 had yeast and warm water, Bottle 2 had yeast, sugar and warm water, Bottle 3 had sugar and water and Bottle 4 has sugar and yeast. We made predictions about what would happen and also observed what was happening during the experiment. After 1 hour this photo shows what had happened.It is clear that in Bottle 2 the balloon inflated faster and bigger than the rest. After discussing our findings (and some more research) we discovered that sugar is food for the yeast and the water activates the yeast. The reaction between the yeast, sugar and warm water creates the gas called carbon dioxide which causes the balloon to inflate.
Today we continued our investigation to see which temperature the yeast likes best. Again, we placed yeast and sugar in bottles. We added cold water to bottle 1 (white balloon), warm water to bottle 2 (green balloon) and boiling water to bottle 3 (red balloon). We made predictions and recorded our observations. This is what the bottles looked like after 45 minutes. What do you think has happened in each bottle?
What temperature do you think yeast likes the best?
We also know that yeast is a very important ingredient in bread. We are going to make some bread soon.
Can you explain why yeast is important in breadmaking? Do our Science experiments help you to understand?