I bought this Petri dish set on Amazon (http://amzn.com/B000NNCI68) for a project, but then decided not to pursue the experiment I was thinking of.

If you or your kid is thinking of doing a science fair experiment (or just an experiment for fun), then this could be perfect for you. It comes with 20 Petri dishes and all the materials you need to test whatever it is you want to test---E. Coli, etc.

Everything is unopened and in the box it came in.