1/4 cup white vinegar
1 tsp salt
1/2 cup water
2-3 drops of dish soap
2 glass bowls
1. Mix 1/2 cup of water and dish soap (left bowl). Mix 1/4 cup white vinegar and salt (right bowl).
2. Add pennies to each. Wait for 10 seconds remove.
3. Analzye: Soap water the pennies will be dirtier than the vinegar pennies because the acid in the vinegar ate away the dirt on the pennies.
4. Watch the smiles and the anticipation on what is going to happen to the pennies.