Materials Spotlight: Racks and Tubes
Racks and Tubes, The Test Tubes - they may go by different names, but they’re all the same: a gloriously detailed Montessori division material. Introduced to the child somewhere around the end of lower elementary or beginning of upper elementary, the tiny parts are appealing. Adults who have had an opportunity to see the Racks and Tubes used are usually delighted by the way this physical material is able to help children understand more deeply how numbers are manipulated during division.
This is something so much more than when we learned with paper and pencil. Of course, that is taught simultaneously, but having the material makes everything make more sense.
A whole lot more complicated than math materials the child has previously used, there are many components, including:
Seven test tube racks. Three of the racks are white: the tubes in one contain green beads (units/ones), another has tubes filled with blue beads (tens), and the last is filled with red beads (hundreds). This pattern is repeated with three gray racks and tubes filled with beads (thousands, ten thousands, hundred thousands). The final rack is black, and its green beads represent millions.
Seven bowls with external colors to match the racks and internal colors to match the beads.
Four wooden frames, each with 81 holes in which beads may be placed.
The color scheme of green, blue, and red being representative of units, tens, and hundreds is repeated throughout many Montessori materials. The child will have already seen this when using the stamp game, bead frame, and checkerboard materials.
As an example, we will refer to the division problem 9,764/4=2,441. We begin by laying out the green board. The other boards will not be used for this problem, because the divisor (4) is only one digit. Larger problems require more boards (more on that later).
To represent the divisor, we will take out four green skittles and set them into place at the top of the board.
The first four racks are all we will need for this problem, so we will take those out along with their corresponding cups.