# Lesson Plan: Solving One-Step Equations using Addition or Subtraction

By Ginean Royal

This is a lesson plan that will demonstrate to students how to solve one-step equations by using addition and subtraction.

Once the students have learned how to write equations (a) translating sentences into equations and (b) translating equations into sentences, the students will now solve one-step equations using addition and subtraction.

Common Core State Standards

A.REI.1: Explain each step in solving a simple equation as following from the equality of numbers asserted at the previous step, starting from the assumption that the original equation has a solution. Construct a viable argument to justify a solution method.

A.REI.3: Solve linear equations and inequalities in one variable, including equations with coefficients represented by letters.

Mathematical Practice(s): 6. Attend to precision

Learning Target(s)

• I can apply order of operations and inverse operations to solve equations
• I can construct an argument to justify my solution process

Essential Question(s)

In what ways can the problem be solved and why should one method be chosen over another?

Vocabulary: inverse operation, isolate, variable, constant

## LESSON - Solve by Adding

Notes:

• Instruct that minus and negative are equivalent
• GOAL: to isolated the specified variable
• Instruct that what is done on one side of the equation (= sign), must be done on the other side of the = sign.

Problem: k – 16 = 12

Step 1: Identify the variable we are solving for: (k)

Step 2: To isolate that variable, you must do the inverse operation to get zero by the variable (cancel out). For example: if you have +6 by the variable, you would subtract 6 from both sides of the equation and vice versa.

K – 16 = 12

+16 +16

Step 3: Add or subtract (depending on your signs) your constants:

K – 16 = 12

+16 +16

K = 28 (-16 + 16 = 0, so you don’t have to write it)

Guided Practice: 3-6 practice problems. You can do 1or 2 problems with the students at the board (Smart Board, Elmo, etc.) and then put them in small groups of no more than 3 to do the rest. These problems can be pulled from any textbook or other resource.

ACTIVITY:

• Go to www.thatquiz.org
• Click on algebra (under integers)
• Choose the length you want (10 is the minimum)
• Choose the level you want. Level 1 is simple one-step equations
• Check Solve (x) only
• This website can be used for many other topics also. Please browse this free website.

Independent Practice: 10-15 problems to be done alone. These problems can be pulled from any textbook or other resource.

Closure/Review: Ask 1-3 questions relating to today’s lesson to be answered by the class as a whole. This will give you a general idea of the class’ understanding of today’s topic.

Exit Ticket: This is to be done the last 3-5 minutes of class and given to you (by hand or in a designated area of your room) as they leave class. Possible questions:

1. Define in your own words or provide an example of isolate, variable and constant.
2. Solve x – 16 = 10.
3. What is the inverse of +6?