By Pat Murphy, The Scientists of Klutz Labs
Not really a book but a boxed kit that comes with parts, for building ten moving LEGO machines that trigger each other.
Buy this one knowing it's a box, not a book. Inside is a 78-page instruction booklet plus the extra parts you need: little LEGO elements, balls, string, paper ramps and funnels and a bucket. Your child follows the steps to build ten machines that actually move, spin, swing, roll, lift, drop, and then links them so one sets off the next, like a marble run made of contraptions. It's the physics of cause and effect turned into an afternoon on the floor. They will need some of their own basic bricks from the bin too, so it works best for a child who already has LEGO, not as a first-ever set.
This turns a LEGO obsession toward how things move, and it does it with a real payoff in their hands, a machine that works. Reading the numbered steps to build it is reading a reluctant builder will happily do, because the reward is immediate and physical. And chaining the machines is where the real play starts: they'll spend far longer inventing their own reaction than they spent building the ten in the book.