Reveal Math Grade 1, Unit 6: Subtraction Strategies to 20
In this unit, your child subtracts within 20 using strategies like counting up from the smaller number and thinking of the matching addition fact. They solve story problems where the missing number can be anywhere. This builds on last unit's adding within 20 and leads into counting and comparing numbers to 120.
By Robert “Bobby” BarnettMath teacher, parent, and founder of Bobby’s Math Club
What is my child learning in Unit 6?
- Solving subtraction stories within 20, including ones where the start or the change is the missing number. Learn more: Adding and subtracting story problems within 20
- Thinking of 16 - 9 as 9 plus what makes 16, and using a known addition fact to find it. Learn more: Subtracting by finding the missing part
- Subtracting within 20 with strategies like making a ten, as in 14 - 4 = 10 and then 10 - 2 = 8 for 14 - 6. Learn more about adding within 20: Adding within 20 · Learn more about subtracting 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
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
- Count up to subtract while setting the table: "We need 15 cups and have 9 out. How many more?" Let your child count up from 9.
- Tell a missing-start story at bedtime: "Some books were on the shelf. You took 4, and 8 are left. How many were there first?"
- Practice through ten with fingers: for 13 - 5, take 3 to get to 10, then take 2 more to land on 8.
Where kids can get stuck
- Subtracting in a missing-start story when the answer needs adding, getting 4 instead of 12.
- Losing count when counting back by ones from a big number like 17.
- Taking away the wrong amount when going through ten, such as taking 5 and then 5 again for 13 - 5.
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
- difference
- The answer when you subtract one number from another.
- missing part
- The number you add to one part to reach the whole.
- related facts
- An addition fact and a subtraction fact that use the same three numbers.
- make a ten
- Break apart a number so one part fills a ten, like 8 + 5 = 8 + 2 + 3.
- unknown
- The missing number in a problem, often shown as a box or a question mark.
- number story
- A short story that ends with a math question to solve.
Ready to build your child’s confidence with subtracting within 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 Reveal Math Grade 1 Unit 6 cover?
Reveal Math Grade 1 Unit 6 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.