Much like with addition, this week we have been exploring multiple strategies for solving subtraction problems. As we begin to explore the relationship between addition and subtraction, I find that understanding how to represent and solve a problem in a variety of ways strengthens the depth of mastery over the concept. We had a few of those wonderful "Ah hah!" moments with modeling subtraction using counting cubes and a number line as our first instinct may seem to be going right to the standard algorithm to solve tricky subtraction problems.
We also focused a lot on borrowing and regrouping within subtraction. Thinking back to when I was taught subtraction, I remember learning the steps to regrouping without fully understanding what was actually going on within the problem. Hoping to show the standard algorithm steps side by side with counting cubes, I am working to bridge the understanding of how borrowing works. This requires a mastery of place value, knowing that 4 tens is equal to 3 tens and 10 ones, along with a foundational understanding of subtraction in which the numbers cannot switch places like they can in addition. I hope to continue to model borrowing across zeros using counting cubes in hopes that they make sense of the crazy crossing out and regrouping going on in their work.