In the summer I wrote a post about Charlotte's addition algorithm with base-10 blocks.
I sort of thought this would be her algorithm and she would just move away from the blocks.
However, lately I've noticed lots of work with the abacus (her favorite) and base-10 blocks again!
However, her strategy has changed.
Today I started exploring HOW it has changed, asking her questions as I watched her solve.
She told me that she knew she had 7 tens because 3 and 4 tens make 7 total.
Okay, I'm following.
Then, she says that 8 only needs "2 more" to make another ten.
So, she grabs another ten stick.
She throws it in the pile to make 8 tens.
She immediately grabbed 3 extra units and throw those to the side.
So I ask her "How did you know to grab 3 units?"
Her answer: "Oh, well since you took 2 away from the 5 to give to the 8, there is only 3 left there".
So, I'm totally following her logic and it makes mathematical sense.
and….ya know what?
She is doing the "traditional algorithm".
Is this a bad thing? Absolutely not! She totally has a grasp on what she's doing.
So I show her how to record her work on the board with numbers and no base-10 blocks.
She giggles and does it correctly with 8 more problems.
Kids' brains are awesome.
We….well, we just have to make sure we keep up ;)
