Into Math Grade 2, Unit 1: Addition and Subtraction Within 20
In this unit, your child builds speed and confidence with addition and subtraction facts within 20. They use strategies like doubles and making a ten, link each subtraction fact to an addition fact, and solve one- and two-step story problems. These facts become the building blocks for the place value work that comes next, where numbers grow into the hundreds.
By Robert “Bobby” BarnettMath teacher, parent, and founder of Bobby’s Math Club
What is my child learning in Unit 1?
- Solving one- and two-step story problems by drawing a picture or a bar model and writing an equation to match. Learn more: One- and two-step story problems within 100
- Finding sums and differences within 20 with strategies like making a ten, so 8 + 5 becomes 10 + 3. 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
- Play a card game with ace to 9: each player flips two cards and adds them, and the bigger sum wins. Talk about shortcuts for the hard ones.
- Use snack time for a subtraction story: 'You had 13 crackers and now have 5. How many did you eat?' Ask which addition fact helps, like 5 + 8 = 13.
- Tell a two-step story on a ride: '6 kids are on the bus, 5 get on, then 3 get off. How many are on now?' Let your child explain each step.
Where kids can get stuck
- Counting on fingers from 1 for facts like 8 + 6, which slows down every bigger problem.
- Stopping after the first step of a two-step story and giving the in-between total as the answer.
- Treating 14 - 8 as a brand-new problem, instead of asking what adds to 8 to make 14.
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
- 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.
- 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.
- equation
- A number sentence with an equal sign, like 13 - 5 = 8.
- two-step problem
- A story problem that needs two math steps to solve.
Ready to build your child’s confidence with 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.
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 Into Math Grade 2 Unit 1 cover?
Into Math 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.