Get them some old power tools from a resale shop, a small sledgehammer and teach them to "Focus you fack!" perhaps? That and some Big Clive could lead to a fair

Get them some old power tools from a resale shop, a small sledgehammer and teach them to "Focus you fack!" perhaps? That and some Big Clive could lead to a fair amount of active learning with things that aren't too expensive if you can get them interested in learning what's actually happening to the point of being able to explain it. Edit: power tools to be disassembled, not so much used