Math Expressions Grade 2, Unit 1: Addition and Subtraction Within 20
In this unit, your child sharpens addition and subtraction within 20 and learns to see the story behind a math problem. They use make-a-ten and doubles strategies, notice how addition and subtraction are related, and solve story problems with a missing part. Strong facts here make the next unit, adding two- and three-digit numbers up to 200, much easier.
By Robert “Bobby” BarnettMath teacher, parent, and founder of Bobby’s Math Club
What is my child learning in Unit 1?
- Solving story problems with a missing total, a missing part, or a missing start, and showing them with drawings and equations. Learn more: One- and two-step story problems within 100
- Building speed with facts within 20, using strategies like doubles plus one and counting on from the bigger number. Learn more about adding fluently within 20: Adding fluently within 20 · Learn more about subtracting fluently within 20
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
- Turn a game of catch into fact practice: each time you toss, call out a fact like 9 + 6. Your child answers before throwing the ball back.
- Make up a missing-part story while you put away groceries: 'We bought 15 apples. 7 are in the bowl. How many are still in the bag?'
- Say a fact like 7 + 8 = 15 at dinner and ask your child for the three other facts in its family. Then let them choose a fact for you.
Where kids can get stuck
- Starting to count at 1 for 9 + 4, instead of starting at 9 and counting on 4.
- Adding every number in a story because it says 'more,' even when the problem asks for a smaller missing part.
- Mixing up a double with a near double, answering 6 + 7 = 12 because 6 + 6 = 12.
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
- addend
- One of the numbers you add. In 8 + 5 = 13, the addends are 8 and 5.
- sum
- The answer when you add. In 8 + 5 = 13, the sum is 13.
- difference
- The answer when you subtract. In 13 - 5 = 8, the difference is 8.
- doubles
- Facts that add a number to itself, like 7 + 7 = 14.
- count on
- Starting at one number and counting up, like 9, then 10, 11, 12, 13 for 9 + 4.
- fact family
- Related facts that use the same three numbers, like 6 + 9 = 15 and 15 - 9 = 6.
- equation
- A number sentence with an equal sign, like 13 - 5 = 8.
Ready to build your child’s confidence with addition and subtraction to 20?
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.
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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 Math Expressions Grade 2 Unit 1 cover?
Math Expressions Grade 2 Unit 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.