## What are the Addition Facts to 20?

The addition facts to 20 are simply the sums from 0+0 up to 10+10. They’re the building blocks of arithmetic, and usually the first math facts that children master. Most schools and math curricula recommend that children master the addition facts by the end of 1st grade (and certainly no later than the middle of 2nd grade).

That’s because the addition facts are so **foundational** to the rest of elementary arithmetic. Without thorough mastery of the addition facts to 20, kids will begin to struggle and flounder as they start to tackle subtraction, word problems, and multi-digit addition in second grade.

These simple little sums may not seem thrilling. But when you teach your kids the addition facts, you’re teaching them **a lot more** than just simple addition.

### Deep understanding

Learning the addition facts helps kids understand the **principles **of addition better. One important principle that kids learn as they master the addition facts is the commutative property. It’s a long name, but all it means is that we can add numbers in any order. For example, 6 + 4 equals 4 + 6, or 7 + 8 equals 8 + 7. (The commutative property also cuts the number of facts that kids need to master; once they know 6+4, they already know 4 + 6.)

Learning the addition facts also prepares kids for regrouping and “carrying the one” when they start adding larger numbers. For example, when kids add 6+5, they discover that they have one group of ten, with one left over, or 11. This is exactly the same kind of thinking they’ll need to do when they start adding two-digit numbers vertically.

## Juggling numbers

We can only juggle so many ideas in our heads at one time. As cognitive scientist Daniel Willingham explains in Why Don’t Students Like School:

“…working memory is the place in the mind where thinking happens—where we bring together ideas and transform them into something new. The difficulty is that there is only so much room in working memory, and if we try to put too much stuff in there, we get mixed up and lose the thread of the problem we’re trying to solve.”

Knowing the addition facts equips kids to grapple with much more complex math concepts. Whether they’re adding fractions, coefficients, or even vectors, kids who know the addition facts have a huge advantage: they can **focus** on the challenging, new material and not get sidetracked by adding.

## Subtraction, multiplication, division? No problem

Once kids have the addition facts mastered, the other basic facts come much easier. The subtraction facts can be thought of as the reverse of addition. (Since 6+7=13, 13-7 must equal 6.) Multiplication is simply repeated adding, so once a child knows how to add well, it’s easy to use repeated adding to begin to master multiplication. Then, once multiplication is mastered, learning division simply requires thinking of the multiplication facts backwards.

## “I think I can, I think I can…”

Kids often feel intimidated when they look at the chart of all of the addition facts to 20. But the great thing about the addition facts is that you know *exactly* what you need to learn. When I teach kids the addition facts, I love showing them the chart of all the facts at the beginning and then tracking their progress. It feels like a daunting task at first, but as the weeks go by, they feel a great sense of accomplishment as their diligent effort pays off.

Being able to take an overwhelming task and break it down into smaller parts is a vital life skill. But when kids learn that they can master the addition facts, they develop confidence that they can do it!

Hi I’m Onika teacher of 6 up to 7 years old. I am struggling to get my students know their addition at this level. Thanks to your page I just realise that there is an addition facts. I will try to teach through this and may report the results and issues if you like.

Hi Kate!

Thank you for your blog. Quick question about addition math facts in 1st grade. When you say three seconds, is that a verbal answer they give to the addition fact or is that including the time needed to write the number down? My son can verbally answer the facts in 3 seconds or less but cannot transfer his answer to paper in that time. We use a hand held math fact thingy and he types in his answer on the screen. Should we be practicing more time tests where he needs to write his answer on the pagd in three seconds or less?

Thank you!

Hi Laura,

Great question! I mean that kids should be able to say the answer verbally within 3 seconds. Their fine motor skills vary too much to have a general rule for writing. In first grade, many children still need 10 seconds just to remember which way the 5 goes. 🙂 It sounds like your son is doing great.

Happy Math!

Kate

Thank you Kate. Just wanted you to know your blog and addition/subtraction books have completely changed how we do math in our house, and we haven’t looked back since!

I’m so happy to hear that, Laura! Thanks for taking the time to let me know. 🙂

Hi Kate, can we use this method of teaching in the UK. Also I noticed you mentioned writing the numbers correctly. My grandson if not concentrating writes his 6 back to front, the 5 seem ok now. Is this normal development. Thanks sandra

Absolutely, Sandra! I talk more about number reversals in this article.

Happy Math!

Kate

Thank you so much I am homeschooling my 5th grader and freshman. This will be our second year. After pulling them from public school I found that even my 8th grader now freshman struggled with math subtraction and multiplication was hard so I decided to start with the facts for addition and move on this year. I happened to just find the YouTube video for them. Do you do subtraction multiplication and division as well?

Yes, I have books for all four sets of facts. You can check out all four here.

Happy Math!

Kate

Would it be too confusing to take a break half way through for 10 days while on vacation?

Not at all! It may even give the facts a little time to percolate and solidify, and you can always do a little review when you get back.

Happy Math!

Kate