Blocks are blocks - the units of wood found in every good pre-school. They fit together in exact multiples; they are fun to play with but they also introduce without fuss and direct teaching mathematical concepts such as addition and subtraction, and spatial concepts such as area, volume and balance. With blocks children can manipulate space as well as their imaginations. Car cases are like blocks you can live in. In well equipped preschools you will find car cases or large boxes specially constructed, and also planks, ladders, cable reels, nets, posts, and possibly forts - outdoor climbing apparatus generally. This climbing equipment can foster mathematical and mechanical understanding, including the concepts of gravity, levers, balance, force, and space.