Solving Equations- Distributive Property

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Objective

SWBAT solve equations that require using the distributive property.

Big Idea

Give a little love! Get kids to distribute to every term within the parentheses while solving equations.

Lesson Author

Jeff Li MTP

New York, NY

Grade Level

Eighth grade

Subjects

Math

Algebra

Linear and Nonlinear Equations

Standards

8.EE.C.7

Solve linear equations in one variable.

8.EE.C.7a

Give examples of linear equations in one variable with one solution, infinitely many solutions, or no solutions. Show which of these possibilities is the case by successively transforming the given equation into simpler forms, until an equivalent equation of the form x = a, a = a, or a = b results (where a and b are different numbers).

8.EE.C.7b

Solve linear equations with rational number coefficients, including equations whose solutions require expanding expressions using the distributive property and collecting like terms.

MP1

Make sense of problems and persevere in solving them.

MP6

Attend to precision.

Warm-up

10 minutes

Each day, students complete a warm-up that usually consists of spiraling the previous day's material, in addition to older material. Warm-up problems also sometimes extend lessons that students have encountered before to more unfamiliar contexts.

In this lesson, #3 provided a particularly rich learning activity.

A rectangle has a height that is five less than triple the base, b. Which of the following shows the perimeter of this rectangle?

Most students who chose the wrong answer chose "3b - 5." This provided a chance to talk about:

- close reading of the problem

- using a diagram to model a situation

- collecting like terms, including with negative numbers.

A task that has a bit of a "gotcha" element tends to stay in kids' minds longer, as long as there is a memorable and understood "aha" moment, which this task has. I love using this as a warm-up problem, particularly as the last problem.