Anti-Number Pairs (Kindergarteners)

The key to number sense is the ability to see how numbers pair together. I call these anti-numbers. One pair of anti-nines is 4 and 5 because their sum is 9.

For example, it is critical that our young Mathletes can identify anti-tens of 10 and 0, 9 and 1, 8 and 2, 7 and 3, 6 and 4, 5 and 5. The best part of this lesson was when several of the children began asking about the anti-tens for numbers like 11 and 12. I challenged them to come up with their own solutions; they came up with 11 and -1, 12 and -2 and so on. 

I challenged them to find the anti-nine number pairs using addition and subtraction. The attached pdf allows them to explore anti-numbers from anti-10 to 20 and provides them with a blank page so they can find anti-numbers of their own.

When I was their age, my parents used to give me numbers from which I would extract as many number pairs as possible. I am sure I drove them crazy as I was hungry for more and more numbers. Let your mathematicians drive you crazy as well. Have fun.