Story problems about length
In 2nd grade, children learn to solve word problems about length within 100 by adding and subtracting, often drawing a ruler or number line to show the problem.
By Robert “Bobby” BarnettMath teacher, parent, and founder of Bobby’s Math Club
Try these with your child
These are real questions from our 2nd grade practice. Tap the speaker to hear one read aloud, or the light bulb for a hint, and talk about the answer together.
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
Why this matters
Because length is easy to picture, it is a friendly place for your child to practice deciding whether a story calls for adding or subtracting. Drawing a ribbon or a number line to show the parts and the whole is a tool they will keep using. In 3rd grade, the same kind of drawing helps with problems about time, liquid volume, and weight.
Where kids 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.
How you can help
- Use a measuring tape and string to act out a story: measure 40 inches of string, cut off 15 inches, and ask your child to predict the length left before measuring it.
- Make up length stories during crafts or gardening, such as "We need 60 centimeters of tape and have 35. How much more do we need?"
- Ask your child to sketch a quick strip or number line for a length problem, labeling each part with its number and unit, before working it out.
The kid-friendly video below explains it in a few minutes, and Bobby's Math Club offers free practice that grows with your child.
Kid-friendly explanation
Questions parents ask
Why is my child solving word problems about lengths?
Lengths are easy to picture, so they help your child see how parts and wholes fit together in a word problem. Drawing a ribbon or a ruler shows whether to add or subtract. These problems also connect measurement, number lines, and addition and subtraction within 100.
What does same units mean in these problems?
It means every length in the problem uses one unit, such as all inches or all centimeters. That way, your child can add or subtract the numbers directly. Problems that mix units, like feet and inches, and require converting come in 4th grade.
How can I help if my child is not sure whether to add or subtract?
Ask your child to draw the problem. A long bar can show the whole length, and smaller bars can show the parts. If the whole is missing, add the parts. If a part is missing, subtract. Acting it out with string and a ruler can make the choice clear.
Make learning math fun
Bobby's Math Club turns 2nd grade math practice into something fun to do together.
- Free, unlimited practice for every child in your family
- Questions matched to your child’s level, a few minutes a day
- Hints when they are stuck, and a celebration when it clicks
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.
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Join the clubNote for teachers: This skill is covered by Common Core math standard 2.MD.B.5: “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.” Learn how Bobby's Math Club can help your students grow. (Common Core 2.MD.5)