Learn on PengiEureka Math, Grade 4Chapter 21: Decomposition and Fraction Equivalence

Lesson 3: Decompose non-unit fractions and represent them as a whole number times a unit fraction using tape diagrams.

In this Grade 4 Eureka Math lesson from Chapter 21, students learn to decompose non-unit fractions and express them as a whole number times a unit fraction, such as writing 4/5 as 4 × 1/5. Using tape diagrams, students build understanding of fraction equivalence by visually representing how repeated unit fractions combine to form non-unit fractions. The lesson connects prior knowledge of multiplication and repeated addition to foundational concepts in fraction decomposition.

Section 1

Connect Repeated Addition to Multiplication of Fractions

Property

A non-unit fraction ab\frac{a}{b} can be expressed as the sum of 'a' unit fractions of 1b\frac{1}{b}. This repeated addition is equivalent to multiplying the whole number 'a' by the unit fraction 1b\frac{1}{b}.

ab=a×1b\frac{a}{b} = a \times \frac{1}{b}

Examples

Section 2

Decompose Fractions Greater Than One

Property

A fraction greater than one can be decomposed into a sum representing a whole number and a remaining fraction. For a fraction ab\frac{a}{b} where a>ba > b, it can be expressed as the sum of the parts that make one whole (b×1bb \times \frac{1}{b}) and the leftover fractional part. For example:

75=55+25=(5×15)+(2×15)\frac{7}{5} = \frac{5}{5} + \frac{2}{5} = (5 \times \frac{1}{5}) + (2 \times \frac{1}{5})

Examples

  • 43=(3×13)+(1×13)\frac{4}{3} = (3 \times \frac{1}{3}) + (1 \times \frac{1}{3})
  • 108=(8×18)+(2×18)\frac{10}{8} = (8 \times \frac{1}{8}) + (2 \times \frac{1}{8})
  • 74=(4×14)+(3×14)\frac{7}{4} = (4 \times \frac{1}{4}) + (3 \times \frac{1}{4})

Explanation

This skill involves breaking down a fraction greater than one, also known as an improper fraction, into two parts. The first part is the group of unit fractions that make one whole. The second part is the group of remaining unit fractions. This decomposition helps to see the mixed number structure within an improper fraction, showing how many wholes it contains and what fraction is left over.

Book overview

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Chapter 21: Decomposition and Fraction Equivalence

  1. Lesson 1

    Lesson 1: Decompose fractions as a sum of unit fractions using tape diagrams.

  2. Lesson 2

    Lesson 2: Decompose fractions as a sum of unit fractions using tape diagrams.

  3. Lesson 3Current

    Lesson 3: Decompose non-unit fractions and represent them as a whole number times a unit fraction using tape diagrams.

  4. Lesson 4

    Lesson 4: Decompose fractions into sums of smaller unit fractions using tape diagrams.

  5. Lesson 5

    Lesson 5: Decompose unit fractions using area models to show equivalence.

  6. Lesson 6

    Lesson 6: Decompose fractions using area models to show equivalence.

Lesson overview

Expand to review the lesson summary and core properties.

Expand

Section 1

Connect Repeated Addition to Multiplication of Fractions

Property

A non-unit fraction ab\frac{a}{b} can be expressed as the sum of 'a' unit fractions of 1b\frac{1}{b}. This repeated addition is equivalent to multiplying the whole number 'a' by the unit fraction 1b\frac{1}{b}.

ab=a×1b\frac{a}{b} = a \times \frac{1}{b}

Examples

Section 2

Decompose Fractions Greater Than One

Property

A fraction greater than one can be decomposed into a sum representing a whole number and a remaining fraction. For a fraction ab\frac{a}{b} where a>ba > b, it can be expressed as the sum of the parts that make one whole (b×1bb \times \frac{1}{b}) and the leftover fractional part. For example:

75=55+25=(5×15)+(2×15)\frac{7}{5} = \frac{5}{5} + \frac{2}{5} = (5 \times \frac{1}{5}) + (2 \times \frac{1}{5})

Examples

  • 43=(3×13)+(1×13)\frac{4}{3} = (3 \times \frac{1}{3}) + (1 \times \frac{1}{3})
  • 108=(8×18)+(2×18)\frac{10}{8} = (8 \times \frac{1}{8}) + (2 \times \frac{1}{8})
  • 74=(4×14)+(3×14)\frac{7}{4} = (4 \times \frac{1}{4}) + (3 \times \frac{1}{4})

Explanation

This skill involves breaking down a fraction greater than one, also known as an improper fraction, into two parts. The first part is the group of unit fractions that make one whole. The second part is the group of remaining unit fractions. This decomposition helps to see the mixed number structure within an improper fraction, showing how many wholes it contains and what fraction is left over.

Book overview

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

Continue this chapter

Chapter 21: Decomposition and Fraction Equivalence

  1. Lesson 1

    Lesson 1: Decompose fractions as a sum of unit fractions using tape diagrams.

  2. Lesson 2

    Lesson 2: Decompose fractions as a sum of unit fractions using tape diagrams.

  3. Lesson 3Current

    Lesson 3: Decompose non-unit fractions and represent them as a whole number times a unit fraction using tape diagrams.

  4. Lesson 4

    Lesson 4: Decompose fractions into sums of smaller unit fractions using tape diagrams.

  5. Lesson 5

    Lesson 5: Decompose unit fractions using area models to show equivalence.

  6. Lesson 6

    Lesson 6: Decompose fractions using area models to show equivalence.