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.
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.
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!