Subtract within 20
Subtracting gives your child a way to answer the questions they ask all day: how many are left, and how many more until it's their turn? Facts like 13 - 4 lead straight into subtracting within 100 next year. And once your child sees that 12 - 8 undoes 8 + 4, every addition fact they know becomes a subtraction fact too. You'll notice it when cookies get eaten or toys are shared.
In this video, your child will learn to subtract within twenty by getting to ten.
The lesson stops at each question for your child's answer.
Three problems, each a little harder
Each problem is worked step by step. Your child will solve the last one before Bobby shows how.
Example 1
12 − 3 = ?
Example 2
14 − 6 = ?
Your child's turn
15 − 8 = ?
The three key steps
- 1Split the number you take away.
- 2Take away down to ten first.
- 3Then take away what's left.
Mistakes to listen for
- Saying the starting number as the first count back, so 13 - 4 goes "13, 12, 11, 10" and comes out as 10, not 9.
- Hearing "how many more" as a signal to add, so "How many more is 15 than 9?" gets the answer 24 instead of 6.
- Counting up to find 12 - 8 but answering with the number they land on, 12, rather than how many they counted, 4.
The lesson shows every step, so your child sees why it works. Read our parent's guide to subtracting within 20 →
Is your child ready to practice what they've learned?
Bobby's Math Club offers unlimited practice for free.
Join the clubMore kid-friendly lessons
More 1st grade Problem Solving, with questions your child answers along the way.
Questions parents ask
Does my child need an account to watch?
No. You can watch this on any device at any time. If your child would like to practice subtracting within 20, and you'd like parent-friendly reports on your child's progress and growth, you can join Bobby's Math Club for unlimited free practice.
What happens when my child answers a question?
A right answer gets a cheer, and the lesson carries on. If your child isn't sure, they can tap "I don't know yet", and Bobby gives the answer and shows another example. Nothing is scored or stored.
Is this the same lesson that's on YouTube?
Yes. Here, the lesson stops at each question and waits for your child to answer. On YouTube, each question stays on screen for a few seconds, and then the lesson plays on.
Where can I learn more?
There's a short, kid-friendly lesson like this one for every Pre-K to 5th grade math skill, all in our video library. Our parent's guide to subtracting within 20 has more on where kids get stuck and how you can help at home. In the club, your child practices at just the right level, about five minutes a day, and you get parent-friendly reports as they grow. Learn more about how it works →
Practice subtracting within 20
Questions at your child's level, about five minutes a day, on subtracting within 20 and whatever PK-5 skills they need to develop. Unlimited practice, free forever.
Join the club