2nd Grade · Measurement & Data
2.MD.B.5: Use addition and subtraction within 100 to solve word problems involving lengths
2.MD.B.5 is a 2nd grade Common Core math standard in Measurement & Data. 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
Use addition and subtraction within 100 to solve word problems involving lengths that are given in the same units, e.g., by using drawings (such as drawings of rulers) and equations with a symbol for the unknown number to represent the problem.
In plain words
Use addition and subtraction within 100 to solve word problems involving lengths.
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
A piece of yarn is 40 cm long. If you add another 30 cm piece to it, what is the total length of the yarn?
- 10 cm
- 70 cm
- 60 cm
Where students can get stuck
- Adding whenever a story says "longer" or "more," even when the shorter length is missing and subtraction is needed.
- Leaving the unit off the answer, writing 27 instead of 27 inches.
- Drawing bars that do not match the numbers, such as a short bar for 45 and a long one for 18.
Effective teaching strategies
- Have students draw a ruler or a bar for each length in the story, label the parts, and decide whether the unknown is a part or the whole.
- Ask students to underline the question and say whether it asks them to put lengths together or find a difference, instead of hunting for the word longer.
- Check each answer for its unit and against the drawing before students call it done, such as a bar for 45 inches that must look longer than a bar for 18 inches.
Units that teach this standard
Find where 2.MD.B.5 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
Eureka Math
Eureka Math²
i-Ready Classroom Mathematics
Illustrative Mathematics
Don’t see your curriculum? Contact Bobby and we’ll see if we can help!
Share it with families
Families can read Story problems about length for a plain-language look at this skill, with three questions to try together and ideas for helping at home.
Help every student practice measurement and data 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.