Cogito
Grade 5 Math · Chapter 2 · Lesson 4
Brackets and Order
Brackets say what to do first.
10 problems · about 15 minutes · 5.OA.A.1, 5.OA.A.2
What this lesson teaches
The child evaluates expressions with parentheses and writes expressions from words.
- Brackets say which part happens first.
- Without them, multiply and divide before adding and subtracting.
- The order changes the answer, so it matters.
Warm-Up Review
From earlier lessons. Loosen up before the new work.
2 problemsReview — A Fraction Is a Division: 5 ÷ 8 as a fraction. What is the top number?
Answer 5
Why 5/8.
Review — Dividing by Two Digits: 552 ÷ 24 = ?
Answer 23
Why 20 + 3 = 23.
Warm Up
Straightforward practice. Get the method working first.
4 problems(9 + 3) × 4 = ?
Answer 48
Why 48.
What do brackets tell you?
Answer Which part to do first.
Why Brackets set the order.
(12 − 4) × 3 = ?
Answer 24
Why 8 × 3.
12 − 4 × 3 = ?
Answer 0
Why 12 − 12.
Build It Up
The same ideas with more to keep track of.
2 problems2 × (15 + 5) = ?
Answer 40
Why 2 × 20.
(20 ÷ 4) + 7 = ?
Answer 12
Why 5 + 7.
Stretch Yourself
Mixed problems. Work out what kind of question it is before you start.
2 problemsWith Brackets: (6 + 4) × 5 = ?
Answer 50
Why 50.
Without Brackets: 6 + 4 × 5 = ?
Answer 26
Why 6 + 20 = 26. Very different.