A couple of fun things to do this Saturday...

Lowe's is having their Build and Grow clinic this Saturday from 10 - 11 am. Go here to register. This project is recommended for kids in grades 1 - 5. It is completely free and a really fun activity to do with your kids.

If you have younger kids, then Michaels is having a fun craft for them from 10 am - 1 pm, while supplies last, so I'd suggest going sooner rather than later! It is recommended for ages 4 and up and is a Science Fair Theme where kids will be able to make their own 3D Molecules out of modeling clay, like the one here...
I don't believe that registration is necessary but you may want to check with your local store, go here to find your closest store.