An Olympia LBS, The Bike Stand, does a free bike maintenance and repair class. Every Monday night from 7PM to 8PM. Sort of a rotating curriculum, and if you go long enough you get everything.
Last week was wheel building. Tonight was wheel trueing. Next week is gear ratios.
Took my 11 year old son tonight. He said he enjoyed it and wants to come back. At times I know his mind was distracted looking at things, but if he picks up a few things now and again, so be it. The instructor, Bill, commented how well behaved and quiet he was. I added it surprised me because he's normally very talkative.
We talked briefly about gear ratios. When we got home, I showed my son my Schwinn. Had him pedal while I held the rear wheel off the ground and switched gears.