Learn on PengiIllustrative Mathematics, Grade 6Unit 6 Expressions and Equations

Lesson 1: Equations in One Variable

In this Grade 6 Illustrative Mathematics lesson from Unit 6: Expressions and Equations, students learn to represent and solve one-variable equations using tape diagrams and balanced-hanger diagrams. Students practice matching equivalent equations such as 4 + x = 12 and 4 · x = 12 to their corresponding diagrams, reinforcing how different equation forms can describe the same relationship between quantities. By drawing diagrams and reasoning about unknown values, students build foundational skills for solving equations in one variable.

Section 1

Modeling Equations with Tape Diagrams

Property

A tape diagram, or bar model, is a visual representation of an equation. The total length of the tape represents the value on one side of the equation, while the segments of the tape represent the terms on the other side. This model helps to visualize the relationship between the parts and the whole in an equation.

Examples

Section 2

The Truth Value of an Equation

Property

An equation is a statement that two mathematical expressions are equal. This statement can be either true (if the values on both sides of the equal sign are the same) or false (if the values are different). For an equation with a variable, the equation is true only for specific values of that variable, which are called solutions.

Examples

  • The equation 5+3=85 + 3 = 8 is a true statement because both sides equal 8.
  • The equation 4×3=104 \times 3 = 10 is a false statement because the left side equals 12, and 121012 \neq 10.
  • For the equation x+5=9x + 5 = 9, the statement is true only when x=4x = 4. If you substitute any other value for xx, the statement becomes false.

Explanation

Think of an equation as a question: "Are the two sides really equal?" If they are, the equation is true. If they are not, the equation is false. When an equation includes a variable, solving the equation means finding the specific value for the variable that makes the equation a true statement.

Section 3

Introduction: Modeling Equations with Balanced Hangers

Property

A balanced hanger represents an equation where the total weight on the left side is equal to the total weight on the right side.
If the left side has weight LL and the right side has weight RR, the balanced hanger represents the equation L=RL = R.

Examples

Section 4

Basic Operations for Two-Step Equations

Property

  1. Add or subtract the same number to both sides of the equation.
  1. Multiply or divide both sides of an equation by the same nonzero number.

Book overview

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Unit 6 Expressions and Equations

  1. Lesson 1Current

    Lesson 1: Equations in One Variable

  2. Lesson 2

    Lesson 2: Equal and Equivalent

  3. Lesson 3

    Lesson 3: Expressions with Exponents

  4. Lesson 4

    Lesson 4: Relationships Between Quantities

Lesson overview

Expand to review the lesson summary and core properties.

Expand

Section 1

Modeling Equations with Tape Diagrams

Property

A tape diagram, or bar model, is a visual representation of an equation. The total length of the tape represents the value on one side of the equation, while the segments of the tape represent the terms on the other side. This model helps to visualize the relationship between the parts and the whole in an equation.

Examples

Section 2

The Truth Value of an Equation

Property

An equation is a statement that two mathematical expressions are equal. This statement can be either true (if the values on both sides of the equal sign are the same) or false (if the values are different). For an equation with a variable, the equation is true only for specific values of that variable, which are called solutions.

Examples

  • The equation 5+3=85 + 3 = 8 is a true statement because both sides equal 8.
  • The equation 4×3=104 \times 3 = 10 is a false statement because the left side equals 12, and 121012 \neq 10.
  • For the equation x+5=9x + 5 = 9, the statement is true only when x=4x = 4. If you substitute any other value for xx, the statement becomes false.

Explanation

Think of an equation as a question: "Are the two sides really equal?" If they are, the equation is true. If they are not, the equation is false. When an equation includes a variable, solving the equation means finding the specific value for the variable that makes the equation a true statement.

Section 3

Introduction: Modeling Equations with Balanced Hangers

Property

A balanced hanger represents an equation where the total weight on the left side is equal to the total weight on the right side.
If the left side has weight LL and the right side has weight RR, the balanced hanger represents the equation L=RL = R.

Examples

Section 4

Basic Operations for Two-Step Equations

Property

  1. Add or subtract the same number to both sides of the equation.
  1. Multiply or divide both sides of an equation by the same nonzero number.

Book overview

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

Continue this chapter

Unit 6 Expressions and Equations

  1. Lesson 1Current

    Lesson 1: Equations in One Variable

  2. Lesson 2

    Lesson 2: Equal and Equivalent

  3. Lesson 3

    Lesson 3: Expressions with Exponents

  4. Lesson 4

    Lesson 4: Relationships Between Quantities