Paper Punch
A square sheet is folded in half, then folded again, and a hole is punched through the small folded square. Where will the holes be when the paper is opened? Think of each crease as a mirror and place the holes on the board.
Tap the squares that have holes, then press Check.
How to play
The pictures above show the order of the folds (dotted lines are creases, arrows show the half that moves). The black dot in the last picture is the hole punched through the folded paper. The 4×4 board below is the paper opened out flat. Tap the squares that should have holes, then press Check. Tap again to remove one. The last hint puts the answer on the board.
Learn more
A crease works like a mirror. When the paper is opened, each hole appears again on the other side of the crease, the same distance away. After two folds, four layers of paper lie on each square of the folded paper, so one punch makes four holes. The tests check every puzzle with two methods that give the same answers: working out where every square of the paper lands in the folded stack, and unfolding crease by crease with a mirror image.