Binomial Cube

The Binomial Cube is a puzzle to the child and the formula (a+b)³ to the adult. Working from the pattern on the lid, a child fits the coloured prisms and cubes back into the box, colour to colour and face to face, and the box itself says whether the placement was right. Later the same layers are built outside the box, from memory, once the arrangement has been met often enough to be remembered. Offered on the sensorial shelf from three years, it comes back years later as algebra that can be held.