We began our science topic on Micro-organisms. We created an experiment using yeast, water and sugar. We had a bottle filled with warm water and one filled with cold water. We mixed in the sugar and yeast and attached a balloon to the neck of the bottle.
The balloons with the warm water quickly began to inflate. The yeast mixture produced carbon dioxide which inflated them.
The mixture with the cold water did not inflate straight away but the next morning we found that the balloons had inflated.