3 weeks ago
My best advice, and my colleagues agree, is to not try to get the students to regroup into a ten when there is a zero and then subtract from the ten to make nine. I tell my students that you regroup from "whoever" is next door. If "someone" is there, then you take 1. If "no one is there, then you keep moving down the street until you find someone home and you subtract from that entire number". So if you're subtracting 89 from 306, you cannot subtract 9 from 6 so you go next door. But no one is there so you keep moving. Using the marker, you have marked through a 30 so you subtract 1 from 30 leaving a 29. Bring back the one you took making a 16. Then you can subtract. It's the same principle but leaving out the middle step and my kids always get it quickly.Versus:
Using whiteboards, I ask, "What is 1 less than 5000?"
We do several of these questions and then move to:
Then there is no regrouping.