Cuisenaire Rods

Cuisenaire rods give students a hands-on elementary school way to learn elementary math concepts, such as the four basic arithmetic operations and working with fractions. In the early 1950s, Caleb Gattegno popularized a this set of colored number rods created by the Belgian primary school teacher Georges Cuisenaire (1891-1976), who called the rods réglettes.

Overview
The educationalists Maria Montessori and Friedrich Froebel had used rods to represent numbers, but it was Cuisenaire who introduced their use to teachers across the world from the 1950s onwards. He published a book on their use in 1952 called Les nombres en couleurs. Cuisenaire, a violin player, taught music as well as arithmetic in the primary school in Thuin. He wondered why children found it easy and enjoyable to pick up a tune and yet found mathematics neither easy nor enjoyable. These comparisons with music and its representation led Cuisenaire to experiment in 1931 with a set of ten rods sawed out of wood, with lengths from 1 cm to 10 cm. He painted each length of rod a different color and began to use these in his teaching of arithmetic. The invention remained almost unknown outside the village of Thuin for about 23 years, until Gattegno came to visit him and observe lessons in 1953. With Gattegno's help, the use of the rods for both mathematics and language teaching was developed and popularised in many countries around the world.

color Length
(in centimeters)
White 1
Red 2
Light green 3
Lavender 4
Yellow 5
Dark green 6
Black 7
Brown 8
Blue 9
Orange 10

The Silent Way
Though primarily used for mathematics, they have also become popular in language-teaching classrooms, particularly The Silent Way. They can be used

to demonstrate most grammatical structures such as prepositions of place, comparatives & superlatives, determiners, tenses, adverbs of time, manner, etc.,
to show sentence and word stress, rising and falling intonation and word groupings,
to create a visual model of constructs, for example the English verb tense system
to represent physical objects: clocks, floor-plans, maps, people, animals, fruit, tools, etc. which can lead to the creation of stories told by the students as in this video.

Other colored rods
In her first school, and in schools since then, Maria Montessori used colored rods in the classroom to teach concepts of both mathematics and length. This is possibly the first instance of colored rods being used in the classroom for this purpose.

Doctor Catherine Stern also devised a set of colored rods produced by staining wood with aesthetically pleasing colors.

In 1961 Seton Pollock produced the color Factor system, consisting of rods from lengths 1 to 12 cm. The odd-numbered lengths have cold colors, and the even-numbered lengths have warm colors.