What I did was, I had a loaf of bread, three zip baggies, gloves, and a class. I put the gloves on and put a piece of bread in a baggie, sealed it and labeled it.
Next, I went to the sink, washed my hand for a whole minute. I then put a slice of bread in a baggie and labeled it.
Then, I grabbed a slice and had EVERYONE pass it around the room. I picked it up at the end and put it in another baggie and labeled it.
I placed all three baggies in a place for everyone to see, we will watch the bread grow mold over the days.
What should happen is that the baggie with the bread that was touched by everyone should grow mold faster than the other two. The less sanitary, the more mold.
Wait for the look on every 7th graders face when they realize that this came from their own hands! Please tell me what you think about this.
The materials are very common ones, so feel free to try this one at home and tell me how it went. As always Comments are welcome and encouraged.