Some ideas

For my 15th birthday we had a 6 ft sub (we ordered the bread from a local bakery and made our own) and a make it yourself sundae bar which was a big hit even for the older kids. For breakfast pancakes are always popular. I remember going to a slumber party and watching a really great film with popcorn and other movie candies, it was really fun. Kids at the 6th grade age also enjoy mystery theme events and even treasure hunts and things that involve searching for clues. On the crafty side you can have them construct their own derby cars like they do at cub scouts (you can get them (the pine cars) from a scout supply place) they can paint them and add racing stripes, numbers and all kinds of stuff. Hope these ideas help some! Good Luck!