Shortcuts - Hard Subtraction 1
Rose was 6 years and 7 months when this video was made.
The Problem
I've got 5 pennies. You've got 3 pennies. How many
more do I have than you have.
What To Look For In This Video
- Rose does not represent the 5 pennies that I have. She only represents (on her fingers) the 3 pennies that she has. She then counts up from 3 to 5. She can see on her fingers that she would need 2 more pennies to have the same number that I have.
- Not only did I not teach Rose to do this, I think that it would be very hard to do so. Thinking carefully about how this process differs from the model making that Rose was taught you have to be impressed with her ability to reason.
- While I am happy that Rose got the right answer, my real interest
is in how she solved the problem. By asking her how she did it:
- I find out what she is thinking,
- she gets practice articulating her reasoning, and
- over time Rose comes to understand that I am teaching her to think - not a collection of rules to be memorized.
- It seems clear that Rose likes doing this kind of work.