Decimal Fraction Board — First Introduction

Decimals extend place value to the right of the unit. The Decimal Fraction Board uses the same colors as the whole numbers but inverts the hierarchy direction. The child sees that 0.1 is a tenth of a unit, 0.01 a tenth of a tenth. Indirect aim: decimal operations, metric measurement, preparation for scientific notation.

• Framework: Montessori
• Unit: Mathematics
• Learning area: Decimal Fractions
• Level: Ages 8-10

Objectives

• Read and form decimal fractions to thousandths (0.1, 0.01, 0.001)
• Understand the decimal point as the fraction boundary
• Compose numbers like 23.456 using the board
• Bridge to decimal operations

Materials

• Decimal Fraction Board (white unit square, green tenths, blue hundredths, red thousandths)
• Decimal place-value cards
• Problem slips
• Recording paper

Instructions

1. Introduce the board: unit in the middle, whole numbers expanding left, decimals expanding right. 2. Place a green tenth: 0.1. 3. Place three green tenths: 0.3. 4. Add a red thousandth: 0.301. 5. Form 23.456 using cards: two tens, three units, four tenths, five hundredths, six thousandths. 6. Read: 'twenty-three and four hundred fifty-six thousandths'. 7. Compare decimals: which is larger, 0.3 or 0.25? 8. Convert 0.25 to a fraction: 25/100 = 1/4.

Educator tip

The naming of decimals ('four hundred fifty-six thousandths') is hard. Practice it aloud; it is a language skill as much as a math skill.

Assessment

Observe accurate formation, correct reading, and understanding of decimal magnitude.

More from Mathematics

• Squaring Chain — Passage from Linear to Squared
• Cubing Chain of 5 — Linear to Cube
• Pythagorean Theorem — Sensorial Proof
• Algebraic Peg Board — Solving Linear Equations
• Fractions — Addition with Unlike Denominators
• Fractions — Multiplication
• Fractions — Division
• Decimal Multiplication