(as an aside, speaking of chemistry sets: I had one or two when I was young and found chemistry fascinating. I haven't seen on in the shops for ages. Are they now deemed too dangerous for modern kids?)
You would be surprised what is considered dangerous today. We should all have died as children. Parents have been warned not to bring food to school for their child's class. The end of cupcakes. The "wisdom" behind this is that a child might have an unspecified reaction, get sick and sue the school.
A rock pile ceases to be a rock pile the moment a single man contemplates it, bearing within him the image of a cathedral.