Cogito
Grade 3 Math · Chapter 5 · Lesson 6
Comparing Fractions With the Same Bottom
Same size pieces, so just count them.
10 problems · about 12 minutes · 3.NF.A.3
What this lesson teaches
The child compares two fractions with the same denominator.
- Same denominator means same-size pieces.
- So the bigger numerator wins.
- That only works when the pieces match.
Warm-Up Review
From earlier lessons. Loosen up before the new work.
3 problemsReview — Fractions Equal to One: 6/6 equals which whole number?
Answer 1
Why 6/6 = 1.
Review — Fractions on the Number Line: A line cut into 5 parts. How many parts along is 2/5?
Answer 2
Why 2/5 is two parts along from 0.
Review — Fractions as Copies of a Unit: How many copies of 1/8 make 5/8?
Answer 5
Why 5/8 is five copies of 1/8.
Warm Up
Straightforward practice. Get the method working first.
3 problemsWhich is bigger, 3/4 or 1/4?
Answer 3/4
Why 3 fourths beats 1 fourth.
When does counting the top numbers work?
Answer When the denominators are the same.
Why Different denominators mean different-sized pieces.
Which is bigger, 2/7 or 5/7?
Answer 5/7
Why Count the pieces.
Build It Up
The same ideas with more to keep track of.
1 problemWhich is bigger, 7/8 or 6/8?
Answer 7/8
Why Count the pieces.
Stretch Yourself
Mixed problems. Work out what kind of question it is before you start.
3 problemsWhy can you just count when the denominators match?
Answer The pieces are the same size.
Why Look at the bars.
Two Bars: Which is bigger, 4/6 or 5/6?
Answer 5/6
Why 5 sixths is more than 4 sixths.
The Race: Ana ran 3/5 of a lap and Leo ran 4/5. Who ran further?
Answer Leo.
Why 4/5 is more than 3/5.