Solving Equations with Addition and Subtraction (2/4)

Overview

Link to Experience: https://play.phenomena.app/player/yYTdj0I9w3G2lfKjD2FN

Topics: math, algebra, equations, variables

Grades: 8-9

Standards: CCSS.MATH.CONTENT.8.EE.C.7

Duration to complete: 10-15 minutes

Learning outcome: Students will be able to solve one-variable equations by adding to and subtracting from both sides of the equation.

In the Classroom

Pre-Experience (Things to Look Out For):

• If you add or subtract 3 from both sides of an equation, are the two sides still equal?

• Is this true for other numbers, such as 13, 25, or 167?

• How about we generalize it, and subtract “x” from both sides… are the two sides equal then?

• Have you heard of “solving an equation” before? What might that mean?

Post-Experience (Things to Think About):

• In what ways are addition and subtraction similar?

• What strategy might you use to isolate x using addition and/or subtraction?

• Are there any equations that cannot be solved using only addition and subtraction? If so, why? How might you solve them?

• Where have you seen equations before?

• When might it be useful to solve for x?