You build it and you run marbles down it.
I like to watch the marbles go down. You put them in the top and they come out the bottom.
I lose the marbles under the piano because I put 10 marbles in at once. I don’t always but sometimes.
If you get this, don’t get the extension sets until you’re 8 or 9 because it’s hard to build it. I needed help until I got a little bit older.