"To all my teacher friends this is the grossest yet coolest experiment. I did this while teaching about germs and how they spread. You use three pieces of bread. You let all the kids see you put a piece of bread in a baggy with a glove on hence 'controlled' then you wash your hands and put a piece of bread in a baggy for 'clean' last but definitely not least you pass a piece of bread around and let every kid in class touch it then you put it in a baggy and label it dirty. Watch how the bread changes over time due to germs. It is so cool and a great way to teach the importance of hand washing."

Credit: Donna Gill Allen