Working in elementary and middle school classrooms all the time, I friggin' hate those things. But, I must admit, the near-zero friction bearings can be addicting to mess around with. I explained the science behind how they work to a kid one time, and his mind was blown. I heard him telling another kid about the steel weights and kinetic energy and stuff later on like he knew this all along. See, there's a teachable moment in just about everything. Same with the stupid bottle-toss phase from earlier this school year.
In any case, I'm glad both are just about over in schools, as they are all REALLY. FUCKING. ANNOYING. Now, to just wait it out and find out what the new fad is next school year...