Play it · Ages 6–7
The Handshake Problem
Everyone shakes hands with everyone. How many? Three challenges — each one changes what you have to do, not just how many of it there are. Nothing is timed and nothing is scored.
0 of 3 solved
Join every pair of people with a handshake.
Start small on purpose. Count them when you are done.
Four people
Ten minutes of stuck counts as the work.
Now do it away from the screen
The board is the warm-up. The year page has the same problem on paper, the hint ladder, the answer, the five-day week and three questions nobody can mark — which is where the twenty-five minutes actually go.