Cogito
Grade 4 Math · Chapter 5 · Lesson 4
Adding Fractions with the Same Unit
Count the units. The name does not change.
10 problems · about 14 minutes · 4.NF.B.3
What this lesson teaches
The child adds and subtracts fractions with like denominators.
- Add fractions with the same unit by counting the units.
- The bottom number names the unit, so it stays.
- Subtraction works the same way.
Warm-Up Review
From earlier lessons. Loosen up before the new work.
2 problemsReview — Comparing Unlike Fractions: 2/3 written in twelfths has what top number?
Answer 8
Why 2/3 = 8/12.
Review — Equivalent Fractions: 2/3 = ?/9. What is the top number?
Answer 6
Why 2/3 = 6/9.
Warm Up
Straightforward practice. Get the method working first.
4 problems3/10 + 4/10. What is the top number of the answer?
Answer 7
Why 7/10.
Why does the bottom number stay the same?
Answer It names what is being counted.
Why The unit does not change, only how many of it you have.
2/6 + 3/6. What is the top number of the answer?
Answer 5
Why 2 sixths and 3 sixths.
2/6 + 3/6. What is the bottom number of the answer?
Answer 6
Why They are still sixths.
Build It Up
The same ideas with more to keep track of.
2 problems7/9 − 4/9. What is the top number of the answer?
Answer 3
Why 7 ninths take away 4.
Does the bottom number change when you add like fractions?
Answer No. It names the unit.
Why Apples plus apples are still apples.
Stretch Yourself
Mixed problems. Work out what kind of question it is before you start.
2 problemsThe Pizza: Ana eats 2/8 of a pizza and Leo eats 3/8. How much is eaten, in eighths?
Answer 5 eighths
Why 5/8 of the pizza.
The Juice: A jug is 6/10 full. Ana drinks 2/10. How many tenths are left?
Answer 4 tenths
Why 4/10 is left.