There are ten rods differing in length (from 10cm to 100cm). The unit of difference between each rod is 10cm. The rods are painted alternating red and blue, the first section always being red. The child learns to name the numbers and associate it with the quantity. This exercise shows that each number is represented by a single object, as a whole, separate from others.
Children enjoy sorting the number rods by size and this helps the child memorise the sequence of numbers from 1 to 10.