5th Grade · Number & Operations - Fractions
5.NF.A.2: Solve word problems that add and subtract fractions
5.NF.A.2 is a 5th 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
Solve word problems involving addition and subtraction of fractions referring to the same whole, including cases of unlike denominators, e.g., by using visual fraction models or equations to represent the problem. Use benchmark fractions and number sense of fractions to estimate mentally and assess the reasonableness of answers. For example, recognize an incorrect result 2/5 + 1/2 = 3/7, by observing that 3/7 < 1/2.
In plain words
Solve word problems that add and subtract fractions.
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
Sione's pet snail crawls 3/4 foot before lunch and 1/2 foot after lunch. How far does it crawl in all?
- 1 1/4 feet
- 1 foot
- 4/6 foot
Where students can get stuck
- Accepting an impossible answer, like 2/5 + 1/2 = 3/7, without noticing it must be more than 1/2.
- Choosing the wrong operation, adding when the problem asks how much is left or how much more.
- Mixing different wholes, treating half of a small pizza and half of a large pizza as the same amount.
Effective teaching strategies
- Require an estimate before each calculation, such as noticing that 2/5 + 1/2 must be more than 1/2, and use it to reject answers that are too small.
- Ask students to sketch a bar model for each story and circle the clue, such as “how much is left,” that tells whether to add or subtract.
- Show two paper circles of different sizes, each folded in half, and ask why the two halves do not make one whole of either circle.
Units that teach this standard
Find where 5.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
Don’t see your curriculum? Contact Bobby and we’ll see if we can help!
Share it with families
Families can read Story problems that add and subtract fractions 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.