Find a recipe and mix up some bread dough. Is yeast one of the ingredients? (You may also be able to buy some fresh dough at a supermarket; some supermarkets sell dough for making pizza crusts.) Place...

Find a recipe and mix up some bread dough. Is yeast one of the ingredients? (You may also be able to buy some fresh dough at a supermarket; some supermarkets sell dough for making pizza crusts.) Place a ball of dough in a bowl or other container and note how big the ball is. Let the dough sit for an hour. Has the dough risen? Pull it apart. Do you see any evidence of yeast at work?