G8

Copyright © Swun MathCopyright © Swun Math Grade 8 Unit 4 Lesson 3 C TE

Collect Like Terms

Conceptual Lesson

Grade 8 · Unit 4 · Lesson 3
MC: 8.EE. 7 b

Problem of the Day

Objective: I will collect like terms to simplify expressions.

Vocabulary Teacher Resources

Term: a constant, variable, or a number and

variable, multiplied in an expression and

separated by + or ─

Like Terms: terms that have the same

variable, power, or constant

4 a + 5 + 2 a – 3

5 b^2 – 6b + 3b^2

Algebraic Expression: an expression

using variables, integers and operations;

does not have an equal sign

Coefficient: a number used to multiply a

variable

Constant: a number on its own in an

expression or equation

Expression Equation Variable

ퟓퟓퟓퟓ풙풙ퟓퟓ−ퟗퟗ풙풙+ퟑퟑퟑퟑ=ퟕퟕ풎풎+ퟖퟖퟓퟓ

Term Coefficient Constant

Collecting Like Terms

4a + 5 + 2a – 3

(a + a + a + a + 5 + a + a – 3)

6a + 2

Collecting Like Terms:

Distributive Property

3(n + 4) + 4(n + 2)

3n + 12 + 4n + 8

7n + 20

Considerations:

It is helpful to color code like terms using highlighters or

colored pencils. Remember terms are separated by + and –

signs. Signs are always attached to the front of a term.

Remind students to keep the sign of the term when

rewriting. Students should be able to identify that they are

using the commutative property to “rewrite” the algebraic

expressions. Students that are struggling should practice

expanding their expressions.

3x+2b+4x+ b x + x + x + b + b + x + x + x + x + b

Which simplifies to 7x + b. This can help to understand why

we don’t collect 7x + 10b into 10xb (common mistake).

Steps:

1. Expand the expression (if needed).


2. Identify like terms.


3. Reorder the terms.


4. Collect like terms.


5. Simplify.

Application of MPs:

 MP1: Describe in your own words what you are trying to

do.

I am trying to.

 MP6: How did you know your solution is reasonable?

My answer is reasonable since I can prove that

.

1 2 3 4 5 6 7 8

* ^ *

MPs

Applied MP

* Embedded MP

Student Journal Pages

168 - 171