Bridges in Mathematics Grade 2, Unit 8: Measurement Data & Multi-Digit Computation
In this unit, the last of the year, your child brings several skills together. They sort numbers into odd and even, add the rows of arrays, and add and subtract within 1,000. They also measure objects and show the results on a line plot. Arrays, groups of objects arranged in equal rows, are an early step toward the multiplication your child will meet in 3rd grade.
By Robert “Bobby” BarnettMath teacher, parent, and founder of Bobby’s Math Club
What is my child learning in Unit 8?
- Telling whether a group of up to 20 objects is odd or even by pairing them, and writing even numbers as doubles. Learn more: Odd and even numbers
- Finding the total in an array of up to 5 rows and 5 columns by adding the rows, like 4 + 4 + 4 = 12. Learn more: Counting objects in equal rows by adding
- Adding and subtracting three-digit numbers, regrouping across hundreds, tens, and ones, including tricky zeros like 402 − 175. Learn more about adding within 1,000: Adding within 1,000 · Learn more about subtracting within 1,000
- Measuring a set of objects to the nearest inch or centimeter and recording the data on a line plot. Learn more: Measuring things and making a line plot
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
Is 16 an even or odd number?
- Even
- Odd
- Neither
How you can help
- Set out socks or spoons in pairs and ask whether anything is left over. If one is, the number is odd; if not, it is even.
- Point out arrays in a muffin tin, an egg carton, or a window, and ask your child to add the rows to find the total.
- Measure a handful of crayons or pencils, then make a line plot together and talk about which length has the tallest stack of Xs.
Where kids can get stuck
- Struggling to subtract across a zero, as in 402 − 175, where a hundred has to become 10 tens first.
- Adding the rows and the columns, answering 7 for 3 rows of 4 instead of 12.
- Thinking big numbers like 18 must be odd and small numbers must be even.
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
- odd
- A number that can't be split into pairs without one left over, like 7.
- even
- A number that can be split into pairs with none left over, like 8.
- array
- Objects arranged in equal rows and columns.
- row
- A line of objects going across.
- column
- A line of objects going up and down.
- repeated addition
- Adding the same number again and again, like 4 + 4 + 4.
- line plot
- A number line with an X above it for each measurement collected.
- regroup
- Trading 10 ones for 1 ten, or 1 ten for 10 ones, to add or subtract.
Ready to build your child’s confidence with arrays and bigger numbers?
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 Bridges in Mathematics Grade 2 Unit 8 cover?
Bridges in Mathematics Grade 2 Unit 8 covers these math standards. Each one links to what it means, sample questions, and teaching strategies.
- 2.OA.C.3: Determine whether a group of objects (up to 20) has an odd or even number of members.
- 2.OA.C.4: Use addition to find the total number of objects arranged in rectangular arrays.
- 2.NBT.B.7: Add and subtract within 1000.
- 2.MD.D.9: Generate measurement data by measuring lengths of several objects.
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.