Zearn Math Grade 2, Mission 2: Addition and Subtraction of Length Units
In this unit, your child measures length and then adds and subtracts those lengths. They start with centimeters and meter sticks, then move to inches, feet, and yards, estimating first and comparing lengths. They solve length story problems on a number line. It builds on adding and subtracting within 100 and leads into place value, counting, and comparing numbers to 1,000.
By Robert “Bobby” BarnettMath teacher, parent, and founder of Bobby’s Math Club
What is my child learning in Mission 2?
- Measuring with centimeter rulers, meter sticks, yardsticks, and tape measures, and choosing a tool that fits the job. Learn more: Measuring with a ruler, yardstick, or tape
- Measuring one object with two units and seeing that a longer unit, like an inch, takes fewer to cover it. Learn more: Measuring in inches and in centimeters
- Estimating lengths with personal benchmarks, such as a fingertip being about a centimeter wide. Learn more: Estimating lengths in inches, feet, and meters
- Comparing two objects measured in centimeters or inches and finding the difference in their lengths. Learn more: Measuring how much longer one thing is
- Adding and subtracting lengths in story problems, like joining ribbons of 25 and 30 centimeters to make 55 centimeters. Learn more: Story problems about length
- Drawing a number line like a ruler and using jumps to add and subtract lengths within 100. Learn more: Adding and subtracting on a number line
Sample questions to try together
These are real questions from our 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 door is measured using which tool?
- Ruler
- Measuring Tape
- Small paper clip
How you can help
- Find your child's personal benchmarks: measure their fingertip in centimeters and their hand span in inches. Use them to estimate the length of a spoon or a book.
- Measure two toys in centimeters and ask how much longer one is. Use a measuring tape as a number line to count the difference.
- Lay two scarves or ribbons end to end, measure each one, and ask how long they are together. Then check by measuring both at once.
Where kids can get stuck
- Leaving gaps between units when measuring with paper clips or cubes, so the object seems shorter than it is.
- Measuring one object in inches and another in centimeters, then comparing the numbers as if they match.
- Giving the longer object's length instead of how much longer it is than the shorter one.
Practice makes perfect
Bobby's Math Club has practice problems that adapt to your child’s level, each with a detailed explanation and an easy-to-follow video, so your child can build confidence in these skills one step at a time.
Words your child will hear
- centimeter
- A tiny unit of length, about as wide as a child's fingertip.
- meter
- A unit of length equal to 100 centimeters, a little longer than a yardstick.
- inch
- A small unit of length, about as long as a small paper clip.
- foot
- A unit of length equal to 12 inches, about as long as a ruler.
- yard
- A unit of length equal to 3 feet, or 36 inches.
- estimate
- A careful guess about how long or how many.
- benchmark
- Something you know the size of, used to help you estimate, like a fingertip.
- difference
- The answer when you subtract. In 13 - 5 = 8, the difference is 8.
Want to help your child master measuring and adding lengths?
In Bobby's Math Club, your child practices these skills 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.
Join the club
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.
Which math standards does Zearn Math Grade 2 Mission 2 cover?
Zearn Math Grade 2 Mission 2 covers these math standards. Each one links to what it means, sample questions, and teaching strategies.
- 2.MD.A.1: Measure the length of an object by selecting and using appropriate tools.
- 2.MD.A.2: Measure the length of an object twice, using length units of different lengths.
- 2.MD.A.3: Estimate lengths using units of inches, feet, centimeters, and meters.
- 2.MD.A.4: Measure to determine how much longer one object is than another.
- 2.MD.B.5: Use addition and subtraction within 100 to solve word problems involving lengths.
- 2.MD.B.6: Represent whole numbers as lengths from 0 on a number line diagram.
For teachers: Unit names and order vary between editions and districts, so your school’s own materials have the exact sequence. Learn how Bobby's Math Club can help your students grow.