Cogito
Grade 6 Math · Chapter 5 · Lesson 5
Combining Like Terms
Tidying an expression without changing it.
10 problems · about 18 minutes · 6.EE.A.3, 6.EE.A.4
What this lesson teaches
The child collects like terms to write a simpler equivalent expression.
- Like terms have exactly the same letter part.
- Add the counts of like terms; leave unlike terms alone.
- Simplifying changes how the expression looks, never what it is worth.
Warm-Up Review
From earlier lessons. Loosen up before the new work.
3 problemsReview — Writing Expressions from Words: Evaluate 4n − 3 when n is 5.
Answer 17
Why 17.
Review — Equivalent Expressions: 4(n + 3) expands to 4n + what?
Answer 12
Why 4n + 12.
Review — Letters for Numbers: If a = 8, what is 4a − 5?
Answer 27
Why 27.
Warm Up
Straightforward practice. Get the method working first.
3 problemsSimplify 6n + 3n. How many n?
Answer 9
Why 9n.
Simplify 2n + 6n. How many n?
Answer 8
Why 2 and 6.
Simplify 9n − 4n. How many n?
Answer 5
Why 9 take 4.
Build It Up
The same ideas with more to keep track of.
2 problemsCan 3n + 5 be simplified to 8n?
Answer No. They are not like terms.
Why One has an n, one does not.
Simplify 3n + 2 + 4n. How many n?
Answer 7
Why 3 and 4.
Stretch Yourself
Mixed problems. Work out what kind of question it is before you start.
2 problemsThe Check: Simplify 4n + 5n, then evaluate it when n is 3.
Answer 27
Why 27.
The Same Value: Evaluate 4n + 5n when n is 3, without simplifying first.
Answer 27
Why 27, the same answer. That is what equivalent means.