Learn on PengiIllustrative Mathematics, Grade 5Chapter 3: Multiplying and Dividing Fractions

Lesson 7: Concepts of Division (Optional)

In this optional Grade 5 lesson from Illustrative Mathematics Chapter 3: Multiplying and Dividing Fractions, students explore the foundational concepts of division, including interpreting division as equal sharing and as finding how many groups. The lesson builds conceptual understanding that prepares students for dividing fractions by connecting division to real-world contexts and visual models.

Section 1

Understanding Whole Number Division

Property

Division is the process of splitting a quantity into equal groups. For whole numbers, the equation a÷b=ca \div b = c means that the total amount aa is split into bb equal groups with cc in each group, or that aa is split into groups of size bb resulting in cc groups.

Examples

  • If 20 cookies are shared equally among 4 friends, each friend gets 20÷4=520 \div 4 = 5 cookies.
  • If you have 15 apples and you put them into bags of 5, you will have 15÷5=315 \div 5 = 3 bags.
  • 56÷7=856 \div 7 = 8

Explanation

Division helps us solve problems involving separating a total amount into equal parts. This can be thought of in two ways: sharing a total among a known number of groups, or finding how many groups of a certain size fit into the total. For example, 12÷312 \div 3 can mean "12 shared into 3 groups" (4 in each group) or "how many groups of 3 are in 12" (4 groups). This foundational concept of division with whole numbers provides the basis for understanding division with other types of numbers, like fractions.

Section 2

Relating Division to Finding a Missing Factor

Property

Solving a division problem, such as A÷B=?A \div B = ?, is the same as finding the unknown factor in the related multiplication equation, B×?=AB \times ? = A.
The quotient of the division is the unknown factor.

Examples

Lesson overview

Expand to review the lesson summary and core properties.

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Section 1

Understanding Whole Number Division

Property

Division is the process of splitting a quantity into equal groups. For whole numbers, the equation a÷b=ca \div b = c means that the total amount aa is split into bb equal groups with cc in each group, or that aa is split into groups of size bb resulting in cc groups.

Examples

  • If 20 cookies are shared equally among 4 friends, each friend gets 20÷4=520 \div 4 = 5 cookies.
  • If you have 15 apples and you put them into bags of 5, you will have 15÷5=315 \div 5 = 3 bags.
  • 56÷7=856 \div 7 = 8

Explanation

Division helps us solve problems involving separating a total amount into equal parts. This can be thought of in two ways: sharing a total among a known number of groups, or finding how many groups of a certain size fit into the total. For example, 12÷312 \div 3 can mean "12 shared into 3 groups" (4 in each group) or "how many groups of 3 are in 12" (4 groups). This foundational concept of division with whole numbers provides the basis for understanding division with other types of numbers, like fractions.

Section 2

Relating Division to Finding a Missing Factor

Property

Solving a division problem, such as A÷B=?A \div B = ?, is the same as finding the unknown factor in the related multiplication equation, B×?=AB \times ? = A.
The quotient of the division is the unknown factor.

Examples