For science we observe different types of coins by using a magnifying glass and then talk about things that are alike and things that look different.
This project is great for 2yrs and up. It is really simple but the kids really seemed to like it. If you take a cup of vinegar and little bit of salt and mix it together then drop a really dirty penny into the solution it will clean the penny. The kids really enjoy watching it go from dirty to clean right in front of their eyes.