We also had the FIRST science club in this house!!! We focused mostly on constellations. I thought we had some pretty magical moments. We went into my dark storage area and brought out Maxwell's constellation globe. They passed it around while I read greek myths about the constellations.
They also made their own constellations and we talked about how constellations are completely dependent on your viewing perspective. The kids had a good question: How far away from earth would you need to be before the constellations don't look familiar? I have no idea. Good science fair question.