What it teaches
Sorting things into living, once living, and never alive. The middle group is the whole point. A wooden table, a woollen jumper, a leather shoe and a piece of paper were all alive once, and a child who has never been asked about them assumes they belong with the rocks.
Underneath is the idea that life is a property of matter rather than a kind of matter — a long way from being said in those words, but it starts here.
How it works
A thing appears and the three groups are the answers. Three levels change how many questions a round holds and how many groups are offered.
On a wrong answer the help asks what the thing is made of, which is the question that settles nearly every hard case in this game.
What to look for
The arguments are the good part. Is a seed alive? Is an egg? Both are, and both surprise children. A disagreement here is worth more than a right answer.