Cogito
Grade 5 Math · Chapter 7 · Lesson 2
Dividing a Unit Fraction by a Whole Number
Share a small piece among several.
10 problems · about 15 minutes · 5.NF.B.7
What this lesson teaches
The child divides a unit fraction by a whole number and explains the result.
- Sharing a fraction among several makes smaller pieces.
- Multiply the bottom number by the whole number.
- This is the opposite direction from the last lesson.
Warm-Up Review
From earlier lessons. Loosen up before the new work.
2 problemsReview — Dividing a Whole Number by a Unit Fraction: 6 ÷ 1/3 = ?
Answer 18
Why 18 thirds fit into 6.
Review — Multiplying Mixed Numbers: 1 1/2 × 6. What is the answer?
Answer 9
Why 9.
Warm Up
Straightforward practice. Get the method working first.
4 problems1/3 ÷ 4. What is the bottom number?
Answer 12
Why 1/12.
Which makes the answer bigger?
Answer Dividing a whole number by a fraction.
Why Dividing by a fraction counts how many fit, so the answer grows.
1/4 ÷ 2. What is the bottom number?
Answer 8
Why 4 × 2.
1/5 ÷ 3. What is the bottom number?
Answer 15
Why 5 × 3.
Build It Up
The same ideas with more to keep track of.
2 problems1/2 ÷ 5. What is the bottom number?
Answer 10
Why 2 × 5.
Does 1/2 ÷ 3 give something bigger or smaller than 1/2?
Answer Smaller.
Why It is being shared out.
Stretch Yourself
Mixed problems. Work out what kind of question it is before you start.
2 problemsThe Shared Half: 1/2 ÷ 4. What is the bottom number of the answer?
Answer 8
Why 1/8.
The Shared Third: 1/3 ÷ 2. What is the bottom number of the answer?
Answer 6
Why 1/6.