Dr. Montessori originally designed this piece of material and called it the Frosted Glass Decimal Board. When she commissioned the factory in Italy to produce it, it was printed on a color-coded glass surface on which the student could write numbers, make large multiplications with decimals, and easily erase them as needed. The board was sold by Gonzagarredi until about the mid-1970's. When the supply ended, the product was discontinued. Through the years, however, AMI training centers continued to give the Montessori presentations for this equipment. The Albanesi Educational Center has now developed a modern version of this color-coded board. Instead of a glass board, we have designed a laminated chart and loose, movable number cards that can be placed on the board to form the multiplicand, the multiplier, and the resulting product of a multiplication. On the far left of the board there is a column reserved for the gray number cards of the multiplier. The central part of the board is divided into color-coded stripes. From left to right, the first four sections are for the whole numbers, from units of thousands to simple units. The numerals 1,000 - 100 - 10 - 1 are printed in their respective color-coding across the top of the chart to represent the columns of the whole numbers. Under each numeral, the hierarchic name is printed in red. A black vertical line divides the section of the whole numbers from the other five stripes for the decimal numbers, from the tenths to the hundreds of thousandths. The decimal numerals are printed according to their color-coding and the words are printed underneath in black. The number cards are included with the board. Note:
To carry out the exercises of large multiplications with decimal numbers, the student will also need special color-coded graph paper for writing each result obtained from computations done with the number cards on the board. To order the color-coded math paper that corresponds to the Decimal Board of Multiplication, please see the Math Paper for the Decimal Board of Multiplication (SKU: F-404). Lesson presentation notes are also available as a downloadable PDF file at www.aecmontessorifiles.com
for teachers who did not receive the information on this material in their Montessori Teacher Preparation Course.