Shortcuts - Easy Addition

Eva was 8 years and 7 months at the time that this video was made.

The Problem

You have 29 gumdrops and I have 27 gumdrops. How many gumdrops do we have altogether?

What To Look For In This Video

I always encourage children to "think out loud." Otherwise, I cannot help with whatever process they are using. I also think that it is helpful for them to learn to explain their reasoning.
Instead of adding 29 + 27 Eva adds 30 + 30 and then subtracts 4.
- 29 = 30 - 1
- 27 = 30 - 3
- 29 + 27 = (30 - 1) + (30 - 3) = (30 + 30) - (1 + 3) = 60 - 4 = 56
I was quite surprised that she used this process. My experience has been that almost all children who haven't been taught otherwise will solve this problem by reasoning
- 20 + 20 = 40
- 9 + 7 = 16
- so 29 + 27 = 40 + 16 = 56.
As good as Eva's solution was, I wanted to suggest this other method to her.
Eva finds 9 + 7 in two different ways.
- 9 + 7 = 9 + (9 - 2) = (9 + 9) - 2 = 18 - 2 = 16
- 9 + 7 = 9 + (1 + 6) = (9 + 1) + 6 = 10 + 6 = 16

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