4th Grade · Number & Operations - Fractions
4.NF.A.2: Compare fractions with different denominators, like 2/3 and 5/6
4.NF.A.2 is a 4th grade Common Core math standard in Number & Operations - Fractions. Here’s what it really covers, and how you can help your students learn it.
By Robert “Bobby” BarnettMath teacher, parent, and founder of Bobby’s Math Club
The standard
Compare two fractions with different numerators and different denominators, e.g., by creating common denominators or numerators, or by comparing to a benchmark fraction such as 1/2. Recognize that comparisons are valid only when the two fractions refer to the same whole. Record the results of comparisons with symbols >, =, or <, and justify the conclusions, e.g., by using a visual fraction model.
In plain words
Compare fractions with different denominators, like 2/3 and 5/6.
Sample questions from student practice
These questions from Bobby's Math Club are the kinds of questions your students will see. You can try answering them to see what a student might see.
Question 1 of 3
Kai drinks 1/2 of his bottle of juice. Zoe drinks 1/2 of her bottle of juice. Zoe drinks more juice than Kai. How can that be?
- 1/2 of a bottle is always the same amount
- Zoe's bottle is bigger than Kai's
- Zoe's bottle is smaller than Kai's
Where students can get stuck
- Thinking bigger numbers mean a bigger fraction, so 3/10 seems greater than 2/3.
- Thinking 1/8 is bigger than 1/4 because 8 is bigger than 4.
- Changing only the bottom number to get a common denominator, rewriting 2/3 as 2/6 to compare with 5/6.
Effective teaching strategies
- Fold two same-size strips so thirds are cut into sixths, and have students rewrite 2/3 as 4/6 before comparing it with 5/6.
- Use 1/2 as a benchmark and ask whether each fraction is less than, equal to, or more than one half, as with 3/10 and 2/3.
- Compare 1/4 and 1/8 on folded strips and ask what happens to the size of each piece as the denominator grows.
Units that teach this standard
Find where 4.NF.A.2 lands in the program you teach. Each unit has a guide written for families. Unit names and order vary between editions and districts, so your school’s own materials have the exact sequence.
Bridges in Mathematics
enVision Mathematics
Everyday Mathematics
i-Ready Classroom Mathematics
Illustrative Mathematics
Math Expressions
Reveal Math
Don’t see your curriculum? Contact Bobby and we’ll see if we can help!
Share it with families
Families can read Comparing fractions like 2/3 and 5/6 for a plain-language look at this skill, with three questions to try together and ideas for helping at home.
Help every student practice fractions at home
In Bobby's Math Club, students practice at just the right level, with a hint when they need one, a clear explanation after every question, and kid-friendly videos. Unlimited practice is free for every family.
See how it works for teachers
Written by Robert “Bobby” Barnett
Bobby is an award-winning math teacher, the author of Meet Every Learner’s Needs, and the father of two elementary-school math learners. He uses Bobby’s Math Club with his own kids a few times every week. Learn more or contact Bobby.