## Reflection: Coherence Combining Like Terms - Section 3: Mini Lesson

It's important to emphasize to students that the sign in front of the variable is part of the coefficient and in turn should be included in the shape. This is important when there are several like terms to combine.  For example, students may think 4x + 6y + 3x - 2y is equivalent to 7x+8y, rather than 7x + 4y.

When I realized that students were making this mistake we worked through a few more examples together.  I had students come up to the board and identify the like terms using the shapes method.

1)     9a + c - 2a + d - 3a + 4d

2)     23x + 5y + 6z - 18x + 61y - 5z

3)     41xy + 8z + 2yx + yz - 6z

Including the Sign
Coherence: Including the Sign

# Combining Like Terms

Unit 14: Algebra
Lesson 7 of 16

## Big Idea: How can we use order of operations to simplify expressions?

Print Lesson
9 teachers like this lesson
Standards:
Subject(s):
Math, algebraic expression, Algebra, combining like terms
45 minutes

### Ursula Lovings

##### Similar Lessons

###### Identifying Equivalent Expressions
Big Idea: Properties of operations allow mathematicians to rewrite expressions with equivalent expressions and recognize multiple representations of an expression.
Favorites(15)
Resources(17)
New Haven, CT
Environment: Urban

###### Working with Expressions and Equations Part 3
6th Grade Math » Expressions, Equations, & Inequalities
Big Idea: Ben’s mom gives him the option of grooming 3 horses or mowing 2 fields. Which job should Ben choose? Why? Students use their knowledge of algebraic expressions and equations to write expressions and equations.
Favorites(13)
Resources(20)
Somerville, MA
Environment: Urban

###### Solving Linear Systems of Equations with Substitution (Day 1 of 3)
Algebra I » Systems of Linear Equations
Big Idea: Students will understand the idea of substitution with symbolic and written comparisons.
Favorites(70)
Resources(22)
Washington, DC
Environment: Urban