6.EE.A.3+A.4 6th Grade Expressions & Equations

Combining Like Terms

Apply the properties of operations to generate equivalent expressions, and identify when two expressions are equivalent no matter what value is substituted.

How to explain it

At this standard, students simplify expressions by identifying and combining like terms.

The anchor students hold onto: Only LIKE TERMS can be combined. Constants and variable terms are DIFFERENT types — they cannot be added together.

Sheet #20 Distributive Property connects directly — CLT gathers terms (3n+2n=5n) while distribution expands them. Both skills together prepare students for writing and solving equations.

Worked examples

Example 1

Simplify: 3n + 2n

Step 1Identify like terms: 3n and 2n (same variable)

Step 2Add coefficients: 3 + 2 = 5

Step 35n

Answer5n

Example 2

Simplify: 5x + 3 − 2x

Step 1Variable terms: 5x and −2x; constant: 3

Step 25x − 2x = 3x

Step 33x + 3

Answer3x + 3

Common mistakes

What students write Student combines 3n + 2 to get 5n (treats constant as a like term).

The fix 3n and 2 are NOT like terms — one has a variable, one is a constant. Answer stays 3n + 2.

Try this A student simplifies 3n + 2 and writes 5n. Identify the error and give the correct simplified form.

What students write Student says the coefficient of n is 0 and drops the variable term.

The fix When no number is written in front of a variable, the coefficient is 1, not 0. n = 1n.

Try this A student simplifies 4n + 3 + 2n and writes 9n. Identify the error and find the correct answer.

Teacher tip

Head off the two predictable errors before they happen. First: 3n and 2 are NOT like terms — one has a variable, one is a constant. Answer stays 3n + 2. Second: When no number is written in front of a variable, the coefficient is 1, not 0. n = 1n.