Three Digits with Numerals (2)
In her previous work, the student
solved the problems without recording any of the steps of her logic. Now, with problems
that require 2 exchanges, I encouraged her to record her thinking. The record of her steps
is a proof that her answer is correct.
In the weeks that followed, I did go on to teach this student the standard subtraction algorithm - working from
right to left and "borrowing" when necessary. Unlike what I have done so far, now I had
her "do it my way," with a focus on getting her to execute the procedure with little, or
even no thought, about the justification for each step.