Gymnastick

The motor actually makes the whole block creation move, which my kids thought was the coolest part. It snaps onto regular bricks without any fuss, so they were building spinning contraptions within minutes.

My 9-year-old figured out how to wire the motor to the battery pack in about ten minutes, and now the little guy zips across the kitchen floor like it's alive. The pieces snap tight to standard blocks, which means he keeps rebuilding it into something new every afternoon.

The motor actually clips onto the blocks we already had, so my daughter rebuilt her whole castle into something that spins. She's six and got the wiring right on the second try, which says a lot about how clear the connections are.