Will it fold?
Six squares, joined edge to edge. Imagine cutting the shape out of card and folding along every line. Does it fold into a cube? Decide first, tap your answer, then watch it fold.
Show all eleven nets (this gives the game away)
Tap one to watch it fold.
What's going on
A flat shape that folds up into a cube is called a net of the cube. There are 35 different shapes you can make from six squares, if a shape turned round or flipped over counts as the same shape. Only 11 of them are nets.
A cube has six faces, so each of the six squares has to land on a different face. When a shape without a 2 by 2 block fails, two squares land on the same face and another face is left open. The demo paints the clashing squares red.
Two quick checks save a lot of folding. Four squares round one corner (a 2 by 2 block) never work: they lie flat like a floor tile. Five squares in a row never work either: four in a row already go all the way round the cube, so the fifth lands on top of the first.
Sheet: Eleven ways to unfold a cube.