Nienhuis Montessori, Page 129

3 color-coded keyboards upon which to arrange the bells in chromatic order.

Using the Tens Boards, the child explores the number names of the tens and the sequence of numbers 11-99. Bead quantities are created from the 10 bars and unit beads in the Tens...

This activity provides experience in counting from 1-1000, prepares the child for multiplication and demonstrates in linear form the cube of 1000.