Multiplying Fractions

Unit Review Sheet

These facts and definitions should be mastered throughout this unit. This page can be used for periodic review and study as you are finishing the unit and in the future.

Facts and Definitions

Lesson 1: Multiplying Fractions and Whole Numbers

When you multiply a fraction by a whole number, you multiply the numerator by the whole number and leave the denominator the same. Simplify the fraction or convert to a mixed number as needed.
The keyword "of" often means to multiply. For example, 6 × $\frac{1}{4}$ is "six times one fourth" or "six groups of one fourth."

Lesson 2: What Does Multiplying by a Fraction Mean?

The commutative property of multiplication states that the order of the numbers doesn't matter when multiplying; a × b = b × a
In multiplication, scaling means estimating the value of the product based on the values of its factors.
When you multiply a whole number by a fraction that is less than 1, the product will be less than the whole number.
When you multiply a whole number by a fraction that is greater than 1, the product will be greater than the whole number.
When you multiply a whole number by a fraction that is equal to 1, the product will be the same as the whole number.

Lesson 3: Using Area Models

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Lesson 4: Area Models to Algorithm

To use a number line to multiply two fractions, draw a number line with 0 and the second fraction as endpoints and then use the first fraction's denominator to divide the number line into equal groups. Label the fraction name at each dividing mark. Use the first fraction's numerator to count and shade the required parts, and use the fraction name at the end of the shaded area to find the product.
To use the algorithm to multiply fractions, multiply the numerators in the factors to find the numerator of the product, and multiply the denominators of the factors to find the denominator of the product.

Lesson 5: Multiplying Fractions Trick

With some fraction multiplication problems, you can reduce or cancel fractions before you multiply. This can make it easier to find the product and simplify your answer.

Lesson 6: Multiplying Mixed Numbers

To multiply by a mixed number, first make the mixed number(s) into improper fractions, optionally cancel or reduce if you can, multiply the numerators, multiply the denominators, and then convert the product to a mixed number as needed.

Lesson 7: More Fraction Multiplication

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Lesson 8: Finding Fractional Area

Area is the measure of the space inside a shape or boundary. To find the area of a rectangular shape, multiple the length of one side by the width of another (L×W). Area is expressed in square units.
Tiling is a mathematical method for finding area that involves determining how many square units fit inside a given space.
Perimeter is the distance around a shape. To find perimeter, add together the length of all of the sides.

Lesson 9: Unit Review and Test

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Final Project: Product Sorting Game

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