Reveal Math Grade 2, Unit 2: Fluency with Addition and Subtraction Within 20
In this unit, your child works toward knowing addition and subtraction facts within 20 quickly and by heart. They practice strategies like making a ten, using doubles and near doubles, and thinking of a related addition fact to subtract. It builds on the story problems from the first unit and leads into equal groups, odd and even numbers, and arrays.
By Robert “Bobby” BarnettMath teacher, parent, and founder of Bobby’s Math Club
What is my child learning in Unit 2?
- Finding sums and differences within 20 quickly with mental strategies like making a ten, doubles, and related facts, working toward knowing them by heart. 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
Which subtraction has the same answer as 10 - 3?
- 15 - 8
- 13 - 3
- 15 - 7
How you can help
- Play 'Make 10' with a deck of cards from ace to 9: find pairs that add to 10, like 7 and 3. Then use that pair to solve 7 + 5.
- Practice doubles on a walk or ride: you say '8 plus 8,' your child answers, then you ask '8 plus 9?' Talk about how the two facts are related.
- At snack time, say, 'I had 12 crackers and now have 7. How many did I eat?' Ask which addition fact helps, like 7 + 5 = 12.
Where kids can get stuck
- Counting every fact on fingers from 1, even familiar ones like 9 + 6.
- Answering 7 + 8 = 16 because the double 8 + 8 = 16 feels close.
- Treating 15 - 7 as unrelated to 7 + 8 = 15, and counting back slowly instead.
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
- doubles
- Facts that add a number to itself, like 7 + 7 = 14.
- near doubles
- Facts that are one more than a double, like 7 + 8, which is one more than 7 + 7.
- make a ten
- A strategy that fills a ten first, so 9 + 5 becomes 10 + 4.
- fact family
- Related facts that use the same three numbers, like 6 + 9 = 15 and 15 - 9 = 6.
- 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.
Want to help your child master addition facts 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 Reveal Math Grade 2 Unit 2 cover?
Reveal Math Grade 2 Unit 2 covers this math standard. Each one links to what it means, sample questions, and teaching strategies.
- 2.OA.B.2: Fluently add and subtract within 20.
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.