Eureka Math² Grade 1, Module 2: Addition and Subtraction Relationships
In this unit, first graders explore how adding and subtracting are related, so knowing 6 + 4 = 10 also tells them 10 - 4 = 6. They solve story problems, think of subtraction as finding a missing part, and learn that the equal sign means "the same amount as." It builds on counting on from the last unit and prepares them to use properties to make problems easier next.
By Robert “Bobby” BarnettMath teacher, parent, and founder of Bobby’s Math Club
What is my child learning in Module 2?
- Solving take-from and take-apart stories, including ones where the start or the change is unknown. Learn more: Adding and subtracting story problems within 20
- Using an addition fact to subtract, so 10 - 4 is solved by knowing 6 + 4 = 10. Learn more: Subtracting by finding the missing part
- Subtracting within 10 quickly by thinking of the matching addition fact, and starting to subtract within 20. Learn more about adding within 20: Adding within 20 · Learn more about subtracting within 20
- Checking if equations like 10 - 4 = 3 + 3 are true by working out each side. Learn more: What the equal sign really means
- Finding the unknown number in any spot, like ? - 3 = 5 or 9 = 4 + ?. Learn more: Missing numbers, like 8 + ? = 11
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
I had some toy cars. My friend gave me 3 more cars. Now I have 8 cars in total. How many toy cars did I have at first?
- 3
- 5
- 8
How you can help
- Write a fact family on a sticky note, like 3, 7, and 10, and ask your child to write all four facts. Talk about how one fact helps with the others.
- Tell a story with the change unknown: "There were 10 strawberries; now there are 4. How many did you eat?" Ask your child to think 4 plus what makes 10.
- Play "true or false" while you walk: "Is 6 + 2 the same as 4 + 4?" Ask your child to explain why each side is or isn't the same amount.
Where kids can get stuck
- Subtracting 3 from 5 to get 2 for ? - 3 = 5, when the missing number is 8.
- Calling 4 + 1 = 5 + 2 true because 4 + 1 does make 5, checking only one side.
- Treating 9 - 5 as brand new without noticing that 5 + 4 = 9 already answers it.
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
- fact family
- Addition and subtraction facts that use the same three numbers, like 3, 4, and 7.
- related facts
- Facts that use the same numbers, like 6 + 4 = 10 and 10 - 4 = 6.
- think addition
- Solve a take-away fact by asking what to add, like 8 + ? = 10.
- equation
- A number sentence with an equal sign, like 5 + 3 = 8.
- equal sign
- The symbol = that means "the same amount as."
- true
- An equation is true when both sides are the same amount.
- false
- An equation is false when the two sides are different amounts.
- unknown
- The number we don't know yet, shown with a box or question mark.
Ready to build your child’s confidence with addition and subtraction?
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 Math² Grade 1 Module 2 cover?
Eureka Math² Grade 1 Module 2 covers these math standards. Each one links to what it means, sample questions, and teaching strategies.
- 1.OA.A.1: Use addition and subtraction within 20 to solve word problems.
- 1.OA.B.4: Understand subtraction as an unknown-addend problem.
- 1.OA.C.6: Add and subtract within 20.
- 1.OA.D.7: Understand the meaning of the equal sign.
- 1.OA.D.8: Determine the unknown whole number in an addition or subtraction equation.
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.