This apparatus was designed by Catherine Stern, a physicist by training and the founder of a Montessori school in her native Germany. Stern and her husband were of Jewish descent, and emigrated to New York City in 1938 to avoid persecution by the Nazis. There she developed these materials, described in her 1949 bookChildren Discover Arithmetic. The equipment was first used in preschools and then in primary schools.
The kit includes diverse wooden cubes, rods, and cases, as well as paper cards and covers. The painted cubes are 11/16” (1.8 cm.) on a side, and the rods are of integer multiples of this length. The rods are painted green (1), violet (2), white (3), brown (4), yellow (5), red (6), light blue (7), orange (8), black (9) and dark blue (10). There is also a unit cube in each of these colors.
A counting board, designed to introduce the names of numbers, has grooves of length 1 through 10 that hold rods of appropriate length. At the top of each groove is an indentation that holds a wooden number marker, that is to say a block marked with a digit. A flat wooden board known as a number guide, marked with the numbers from 1 through 10, fits across the back of the counting board.
The kit also includes 10 so-called pattern boards, boards indented with holes that hold a single cube. The holes are arranged in two columns. There is a pattern board for each number from 1 through 10. These are designed to teach the distinction between even and odd numbers, as well as addition and subtraction of 0, 1, and 2. A set of 10 yellow cardboard cards known as pattern board slides shows the arrangement of cubes for each number.
Also included are a set of 10 number cases, square boxes that hold from 1x1 through 10x10 cubes. Two further 10x10 number cases(known as “unit boxes”) contain a set of 100 cubes and a set of 19 rods (one rod of length 10 and two of each of the shorter lengths). There is also a “number track” that holds up to 10 cubes.
A series of folding paper “subtraction shields,” representing integer lengths, can be placed over cubes to indicate subtraction. One set of 9 of these is made up, another of 8 is uncut and in a wrapper. Finally, there is a set of 10 yellow cards, each marked with a digit from 1 to 10, as well as a card marked with a subtraction sign and another with an equals sign. These “number slides” fit in a folding “number stand.” Also present is a manual of instructions dated 1966.