First you need 1 cup of warm water in a dish. To this you add 2T sugar and a packet of active dry yeast. Once it is dissolved, you pour the mixture in the pop bottle, we made a funnel out of a piece of paper to do this. Once it is in the bottle, stretch a balloon over the top of the bottle. Now, you are going to want a larger balloon and you may want to blow it up a couple time ahead of time so it is stretched good. Then just sit back and watch the balloon blow up. The yeast feeds off the sugar and releases carbon dioxide which is blowing up the balloon. Now, see if your little ones can tell you why bread is so light and airy. Now, I must tell you, I did mess up a bit on ours. I don't get my yeast by the packets, I get it in bulk from our natural foods store, so I measured out a packet worth, I believe 2 1/2t. Well......I used a tablespoon by accident. So our yeast mixture also filled up our balloon. You can imagine how eager the kids were to take that outside to pop it!! If you are interested in experiments like this, I would recomend this website to you. It's called the science of cooking, and it is full of lots of fun experiments related to cooking. http://www.exploratorium.edu/cooking/index.html
