OK, I was surprised by this and your friend might be too, but PLAYDOH and BUBBLES! I hosted an end of the year party today for my daughter's 4th grade class(ages 9-12), and I put playdoh and bubbles in treat bags for them because they were cheap. The teacher and I could hardly keep the boys (or the girls) from playing with the playdoh when it was time to move on to something else. We used the playdoh to play a game where everyone had to model an item and let their tablemates guess what it was suppose to be, and we also had a bubble blowing contest.
String for cats cradle or those braided string friendship bracelets would be good too. This age group likes to be active, IME, and sometimes just needs an excuse or instructions to try something for 'babies'. They like balloon animals too!
FYI, Playdoh is $1.87 for 8 cans and bubbles were 6 bottles for $1.99 at our local Target.