Eureka Math Grade 2, Module 1: Sums and Differences to 100
In this unit, the year starts with addition and subtraction. Your child firms up facts within 20, using strategies like making ten, and then adds and subtracts within 100 by thinking about tens and ones. Story problems tie it together. These quick mental skills get used right away in the next part of the year, when your child adds and subtracts lengths.
By Robert “Bobby” BarnettMath teacher, parent, and founder of Bobby’s Math Club
What is my child learning in Module 1?
- Solving one- and two-step story problems within 100 with drawings and equations, starting with simple adding and taking away. Learn more: One- and two-step story problems within 100
- Practicing facts within 20 until they come quickly, using make ten, doubles, and related facts. Learn more about adding fluently within 20: Adding fluently within 20 · Learn more about subtracting fluently within 20
- Adding and subtracting within 100 in their head by tens and ones, such as 46 + 30 or 70 − 23. Learn more about adding within 100: Adding within 100 · Learn more about subtracting within 100
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
What is 80 minus 20?
- 50
- 60
- 70
How you can help
- Play "Ten Friends" on a walk or ride: you say a number from 1 to 9, and your child says the partner that makes 10. Then try partners for 20.
- Ask quick tens questions, like 46 + 30 or 75 − 40, and ask your child how they knew without counting by ones.
- Tell a two-step story about toys: 18 blocks in a tower, 7 knocked down, 5 put back on. Ask how many blocks are in the tower now.
Where kids can get stuck
- Counting on fingers for facts like 9 + 6 instead of thinking 9 + 1 + 5.
- Adding a ten to the ones place, so 46 + 30 becomes 49.
- Using the in-between total as the answer to a two-step story problem.
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
- make ten
- Filling up a ten first to add, like 9 + 6 = 9 + 1 + 5 = 15.
- related facts
- Adding and subtracting facts with the same numbers, like 8 + 5 = 13 and 13 − 5 = 8.
- tens
- Groups of 10. In 47, the 4 means 4 tens, or 40.
- ones
- Single units. In 47, the 7 means 7 ones.
- sum
- The answer when you add numbers together.
- difference
- The answer when you subtract; it also tells how much more one amount is.
- equation
- A number sentence with an equal sign, like 9 + 4 = 13.
- two-step problem
- A story problem that needs two math steps to solve.
Want to help your child master sums and differences to 100?
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 Eureka Math Grade 2 Module 1 cover?
Eureka Math Grade 2 Module 1 covers these math standards. Each one links to what it means, sample questions, and teaching strategies.
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.