Montessori children are introduced to mathematics in a very simple and concrete way. As the child masters each process he is given a new, more abstract and challenging task. The number rods teach him how to count. In conjunction with this, the sandpaper numbers teach him to recognise the symbols for the numbers 1-9. Once the child has learned to recognise these numbers and can assign the correct number to each rod a new challenge is introduced. The spindle boxes are more difficult for the child but the inbuilt control-of-error allows the child to complete this task without help. Later, the child will form numbers using the golden bead material, will be shown the teens, the tens and concepts such as addition, subtraction, multiplication and division will all follow when the child is ready.