Go Math! Grade 2, Chapter 3: Basic Facts and Relationships
In this unit, your child sharpens addition and subtraction facts to 20. They use doubles, make a ten, and think of subtraction as a missing addend, such as solving 15 − 9 by asking 9 + ? = 15. They also solve story problems. Knowing these facts by heart makes the two-digit adding in the next part of the year much smoother.
By Robert “Bobby” BarnettMath teacher, parent, and founder of Bobby’s Math Club
What is my child learning in Chapter 3?
- Solving story problems with facts within 20, deciding whether to add or subtract, and writing a number sentence. Learn more: One- and two-step story problems within 100
- Using doubles, make a ten, and related facts so that sums and differences within 20 come quickly from memory. 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 quick card game with the ace through 9: flip two cards, say the sum, and ask which strategy helped with the tricky ones.
- Ask a subtraction fact on a walk or ride and then its addition partner, like 13 − 5 and 5 + 8, and talk about why they match.
- Make up quick stories at snack time, like 7 grapes on one plate and 6 on another, and ask how many there are in all.
Where kids can get stuck
- Answering 7 + 8 = 16 because the double 8 + 8 = 16 feels close.
- Treating 15 − 9 as a brand-new problem instead of thinking 9 + 6 = 15.
- Counting by ones on fingers for facts like 8 + 6, which slows everything else down.
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 where a number is added to itself, like 7 + 7 = 14.
- make a ten
- Filling up a ten first to add, like 8 + 5 = 8 + 2 + 3 = 13.
- related facts
- Adding and subtracting facts with the same numbers, like 8 + 5 = 13 and 13 − 5 = 8.
- fact family
- Related facts that use the same three numbers, like 6 + 9 = 15 and 15 − 9 = 6.
- missing addend
- The unknown part in an addition, like the box in 9 + ☐ = 15.
- sum
- The answer when you add numbers together.
- difference
- The answer when you subtract; it also tells how much more one amount is.
- number sentence
- Numbers and symbols that show a math idea, like 8 + 7 = 15.
Want to help your child master basic addition facts?
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 Go Math! Grade 2 Chapter 3 cover?
Go Math! Grade 2 Chapter 3 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.