Games
Summer is a great time for large gatherings.  If the kids need a new game idea, try  Wave .  This game is a cross between hide-n-seek and freeze tag.  It could be played indoors with a small group, but it's best outside with lots of kids and lots of hiding spots.

Science
What is hot air?  Try this experiment where you can actually see how heat changes the volume of air.

Crafts
Looking for a good craft idea that doesn't need lots of supplies.  Keep a box of pipe cleaners handy and the kids can be busy making all kinds of pipe cleaner creations, or try these ideas for pipe cleaner creatures  for younger children.