Lesson 5.2 Expressions & Equations

# Solve One-Step Equations

#### Materials

• CCB Mathematics pages 140 - 143

#### Standards

• MP.1

• Solve real-life and mathematical problems using numerical and algebraic expressions and equations.

#### Objectives

• Understand and write equations

• Solve one-step equations

#### Key Concept

• Use equations to represent situations, and use inverse operations to solve one-step equations.

#### Vocabulary

Tier 2 Solution Equal SignEquationEquivalent EquationsInverse Operations

## Before Lesson

In this lesson, students solve one-step equations. To determine their readiness, write the expressions 12x+2x and 27÷3 on the board. Ask students to simplify the first expression and evaluate the second. Invite students to suggest more expressions that the class can simplify or evaluate.

## Background

Tell students that equations are mathematical sentences. They can be closed, that is have no variables, such as 2+10=12, or they can be open sentences that contain one or more variables, such as 12-x=17. While a closed equation is either true or false, an open equation cannot be determined as true or false until it is solved. Point out that students know 2+10=12 because 12=12, but they do not know whether 12-x= 7 because they do not know what value x is.

## Guided Practice

• Understand and Write Equations
• Solve Equations

## Core Skill

Make Sense of Problems: Allow students time to read the sidebar and ask any questions. Then guide students to understand the importance of the question sentence in a problem, usually the last sentence in a word problem. It can act as an anchor or compass when working through the solution to help keep from getting off track or stopping before the final answer is reached. Some students find it helpful to use the question to write an answer sentence with a blank before starting to solve. For example: Mariska’s school spent _____ to buy the lunches.

Represent Real-World Arithmetic Problems: After students read the text, ask volunteers for examples of when they have used math operations to solve problems in their daily lives. Examples may be calculating the cost of purchases, making a budget, and calculating a tip. Then have students solve the problem at the end. Here is a possible solution Let c = the cost of the copies. Multiply the cost of each copy by the total number of copies to get the total cost.

c = \$0.10 x 150 c= \$15

## Extension

Read Aloud: Have students work in groups. Have one person read Skill Practice question 1, 3, or 4 aloud, while the other group members identify key vocabulary that suggest the operations and values needed to write the equation. Have students define key vocabulary in their own words.

Formulate Routine Problems: Have students write real-life problems that can be solved by using one-step equations such as using an hourly rate to determine how much a person will earn per day, per week, or per month. Refer students to Example 1 on page 140 for an example. Have students write their equations and solutions on separate pieces of paper, exchange problems with a partner, and solve.