Play it · Ages 9–10
Eight Coins, One Light
Two weighings. That is all you get. 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
One coin is lighter. Find it in two weighings.
The balance has three results, not two. Level is information.
Eight coins
left pan
empty
right pan
empty
Tap a coin: tray → left pan → right pan
0 / 2 used
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.