Learn on PengiEureka Math, Grade 5Chapter 21: Multiplication of a Whole Number by a Fraction

Lesson 4: Find a fraction of a measurement, and solve word problems.

In this Grade 5 Eureka Math lesson from Chapter 21, students learn how to find a fraction of a measurement by converting between units such as pounds and ounces, pints and cups, and yards and feet. Students practice multiplying a fraction by a whole number to express fractional parts of larger units as smaller units, then apply this skill to multi-step word problems. The lesson builds fluency with unit conversions and fraction multiplication using tape diagrams and simplifying strategies.

Section 1

Rewrite a Fraction of a Measurement as Multiplication

Property

To find a fraction of a measurement, rewrite the problem as the fraction multiplied by the equivalent value in a smaller unit.

ab of 1 Large Unitab×(number of smaller units)\frac{a}{b} \text{ of } 1 \text{ Large Unit} \rightarrow \frac{a}{b} \times (\text{number of smaller units})

Examples

Section 2

Solve Word Problems Involving a Fraction of a Measurement

Property

To find a fractional part of a measurement in a word problem, translate the problem into a multiplication expression.
This involves multiplying the fraction by the total measurement, after converting the measurement into a smaller, more manageable unit.

Examples

Lesson overview

Expand to review the lesson summary and core properties.

Expand

Section 1

Rewrite a Fraction of a Measurement as Multiplication

Property

To find a fraction of a measurement, rewrite the problem as the fraction multiplied by the equivalent value in a smaller unit.

ab of 1 Large Unitab×(number of smaller units)\frac{a}{b} \text{ of } 1 \text{ Large Unit} \rightarrow \frac{a}{b} \times (\text{number of smaller units})

Examples

Section 2

Solve Word Problems Involving a Fraction of a Measurement

Property

To find a fractional part of a measurement in a word problem, translate the problem into a multiplication expression.
This involves multiplying the fraction by the total measurement, after converting the measurement into a smaller, more manageable unit.

Examples