Ditto for the social aspect. For me, I was a bit older [6th-8th graders], but my social experience was FIRST Lego League [FLL]. Basically, the FIRST robotics

Ditto for the social aspect. For me, I was a bit older [6th-8th graders], but my social experience was FIRST Lego League [FLL]. Basically, the FIRST robotics competition also sponsors competitions for middle schoolers to build LEGO robots using the Mindstorms kit [when I did it, it came with the yellow RCX "brain", now they use the NXT and some more advanced sensors/motors]. The social aspect helped bind our team's programmers & "hardware engineers" together. I was always terrible at building things w/o direction, and some kids weren't great at programming. However, when you all have to work together, you start looking at each other for guidance. Seeing the robot take shape eventually led me to learn about gearing and transmissions. Other kids weren't great at programming, but when you see your hardware do wildly unexpected things, you stop and ask "woah, wait, why did it do that? [programmer], show me why it did that!" -- When they see their hardware misbehave, they start to learn what the power of software really is, and vice versa. That and it's a great precursor to FIRST, which I regrettably never got to participate in.