As part of our Mitvah train project we decided to do a science experiment. We wanted to see how yeast makes the dough rise and so we placed yeast, warm water and a little bit of sugar into a bottle and placed a balloon on the top of the bottle. We left the bottle for a couple of hours and were then really excited to see that the yeast had pushed the air up in the bottle and caused the balloon to inflate!!!! What a lot of fun!!!!!!