Learn on PengiIllustrative Mathematics, Grade 6Unit 4 Dividing Fractions

Lesson 4: Fractions in Lengths, Areas, and Volumes

In this Grade 6 lesson from Illustrative Mathematics Unit 4, students use fraction division to solve real-world comparison problems involving fractional lengths, such as determining how many times as tall one person is compared to another or what fraction of a planned distance a cyclist actually traveled. Students practice dividing mixed numbers by converting them to improper fractions and applying the multiply-by-the-reciprocal algorithm. The lesson builds fluency with writing and interpreting division equations to express multiplicative comparisons between fractional quantities.

Section 1

Comparing Quantities: "Times as Large"

Property

To find how many times as large one quantity is compared to another, you use division. This involves comparing a specific quantity to a reference quantity.

Times as large=Quantity being comparedReference quantity\text{Times as large} = \frac{\text{Quantity being compared}}{\text{Reference quantity}}

Section 2

Translating Comparison Questions: A ÷ B vs. B ÷ A

Property

The order of division depends on the question being asked. These two questions produce reciprocal answers:

  • "How many times as large is AA than BB?" \rightarrow Divide A÷BA \div B.
  • "What fraction of AA is BB?" \rightarrow Divide B÷AB \div A.

Examples

Section 3

Procedure: Dividing Mixed Numbers

Property

To divide quantities given as mixed numbers, you must standardise the format first:

  1. Convert mixed numbers to improper fractions (abc=ac+bca\frac{b}{c} = \frac{ac + b}{c}).
  2. Multiply by the reciprocal of the divisor.
  3. Simplify or convert back to a mixed number if needed.

Examples

Section 4

Finding Missing Dimensions in 2D and 3D

Property

Division is used to find a missing dimension (Length, Width, or Height) when the Area or Volume is known.
This relies on the inverse relationship between multiplication and division.

  • Area: If Area=Length×WidthArea = Length \times Width, then Width=Area÷LengthWidth = Area \div Length.
  • Volume: If Volume=Base×HeightVolume = Base \times Height, then Height=Volume÷BaseHeight = Volume \div Base.

Examples

Book overview

Jump across lessons in the current chapter without opening the full course modal.

Continue this chapter

Unit 4 Dividing Fractions

  1. Lesson 1

    Lesson 1: Making Sense of Division

  2. Lesson 2

    Lesson 2: Meanings of Fraction Division

  3. Lesson 3

    Lesson 3: Algorithm for Fraction Division

  4. Lesson 4Current

    Lesson 4: Fractions in Lengths, Areas, and Volumes

Lesson overview

Expand to review the lesson summary and core properties.

Expand

Section 1

Comparing Quantities: "Times as Large"

Property

To find how many times as large one quantity is compared to another, you use division. This involves comparing a specific quantity to a reference quantity.

Times as large=Quantity being comparedReference quantity\text{Times as large} = \frac{\text{Quantity being compared}}{\text{Reference quantity}}

Section 2

Translating Comparison Questions: A ÷ B vs. B ÷ A

Property

The order of division depends on the question being asked. These two questions produce reciprocal answers:

  • "How many times as large is AA than BB?" \rightarrow Divide A÷BA \div B.
  • "What fraction of AA is BB?" \rightarrow Divide B÷AB \div A.

Examples

Section 3

Procedure: Dividing Mixed Numbers

Property

To divide quantities given as mixed numbers, you must standardise the format first:

  1. Convert mixed numbers to improper fractions (abc=ac+bca\frac{b}{c} = \frac{ac + b}{c}).
  2. Multiply by the reciprocal of the divisor.
  3. Simplify or convert back to a mixed number if needed.

Examples

Section 4

Finding Missing Dimensions in 2D and 3D

Property

Division is used to find a missing dimension (Length, Width, or Height) when the Area or Volume is known.
This relies on the inverse relationship between multiplication and division.

  • Area: If Area=Length×WidthArea = Length \times Width, then Width=Area÷LengthWidth = Area \div Length.
  • Volume: If Volume=Base×HeightVolume = Base \times Height, then Height=Volume÷BaseHeight = Volume \div Base.

Examples

Book overview

Jump across lessons in the current chapter without opening the full course modal.

Continue this chapter

Unit 4 Dividing Fractions

  1. Lesson 1

    Lesson 1: Making Sense of Division

  2. Lesson 2

    Lesson 2: Meanings of Fraction Division

  3. Lesson 3

    Lesson 3: Algorithm for Fraction Division

  4. Lesson 4Current

    Lesson 4: Fractions in Lengths, Areas, and Volumes