Marble race
An evening pause: I actually would do this with my marbles as a child. All you needed was a gentle slope and a way to keep the marbles confined within the track. For me, it was a gap between the carpet and one wall in the living room of our rented apartment. The floor just happened to slope just enough.
What is amazing is how you can’t help but pick a marble and cheer for it.
Hat tip Rex Ridenoure of Ecliptic Enterprises.