## Loading...

# Solve Addition and Subtraction Equations using Inverse Operations

Lesson 6 of 20

## Objective: SWBAT solve addition and subtraction equations using inverse operations

## Big Idea: Not all problems are easy to model or solve using mental math. Use inverse operations to solve equations.

*50 minutes*

#### Introduction

*10 min*

This lesson begins with the essential question: How can we use inverse operations to solve addition and subtraction equations. This builds on the work from the previous day - Solve Addition and Subtraction Equations using Models. So I will show a model for each of the examples. I will ask students how we solve this example. They should know from the previous lesson that I will need to add +7 to both sides in order to isolate the variable.

Some students may like to have whiteboards to draw the models while solving the problems today. I will allow this, but I want students to begin relying less on the model - especially on paper. The models are convenient for relatively low magnitude integers, but don't work quite as well with other rational numbers. I think it is important that students begin to solve these equations in the more abstract manner. This would be an application of **MP8**.

*expand content*

#### Guided Problem Solving

*15 min*

The first 3 guided problem solving problems are similar to the examples. I will give the students about 2 minutes to solve these first 3 problems. I will walk around doing check for understandings here. Some common errors to look out for are students not using the inverse operation to solve. Another error to look out for are students who choose the "wrong" value to undo first. Using GP1 as an example, some students may try to add 4 or subtract -4 from both sides as opposed to removing the 7. Problem GP4 and GP5 can be solved in two ways. Some students may find it easier to use the additive inverse; others may choose to subtract away the negative. I will make sure to bring these two methods to the attention of students as we review the problems. The last two problems involve non-integer rational numbers. The problems today emphasize integers, but I have included a few "simple" non-integer equations as well.

*expand content*

#### Independent Problem Solving

*20 min*

Students will work on the independent section alone. Students will be reminded to refer to their examples and GPS problems when stuck. I will not be answering questions on the first set of problems. I will gently tell students taht we will go over problems in a few minutes. That being said, I may have identified students who still need lots of support. They may not be ready to be successful with independent practice problems. I (or possibly a T.A.) will work with these individuals on additional problems similar to those in the GPS section before having them work independently.

In this section, there are 13 problems. The first 8 are most critical to this lesson, but I do want students to solve problem 9-13. These are problems where students must translate verbal descriptions into equations and then solve.

*expand content*

#### Exit Ticket

*5 min*

Before beginning the exit ticket, I will call on students to summarize how to solve addition and subtraction equations. I may cold call students or give them a chance to turn-and-talk before sharing out.

Students then have 5 problems to solve. Each problem is similar to the types of problems seen before.

Students will know they are successful if they are able to answer at least 4 problems correctly.

*expand content*

##### Similar Lessons

Environment: Suburban

###### Solving Equations by Flow Chart - Working Backwards

*Favorites(6)*

*Resources(7)*

Environment: Suburban

Environment: Urban

- LESSON 1: Simplifying Linear Expressions by Combining Like Terms
- LESSON 2: Expand Algebraic Expressions Using the Distributive Property
- LESSON 3: Factor Algebraic Expressions Using the Distributive Property
- LESSON 4: Linear Expressions and Word Problems
- LESSON 5: Solving Addition and Subtraction Equations Using Models
- LESSON 6: Solve Addition and Subtraction Equations using Inverse Operations
- LESSON 7: Solve One-Step Equations Using Inverse Operations
- LESSON 8: Diagrams of Two-Step Equations
- LESSON 9: Speeding Tickets
- LESSON 10: Translate Verbal Statements to Inequalities
- LESSON 11: Graph Inequalities on a Number Line
- LESSON 12: Solve Inequalities Using Addition and Subtraction
- LESSON 13: Solve Inequalities Using Multiplication and Division
- LESSON 14: Solve Two-Step Equations Using Inverse Operations
- LESSON 15: Equation and Inequality Reteach - Fraction Coefficients
- LESSON 16: Algebraic Expressions and Equations for Shape Patterns
- LESSON 17: Simplify Expressions Containing Fractions by Combining Like Terms
- LESSON 18: Simplify Rational Number Expressions Using the Distributive Property
- LESSON 19: Writing Algebraic Expressions to Solve Perimeter Problems
- LESSON 20: An Introduction To Programming in SCRATCH