Borrowing, Regrouping...it has many names, but each time this traditional subtraction concept comes up I feel it is one of the most difficult for students to visualize and comprehend. I've started doing something with the kidlets that our class has dubbed "Apartment Subtraction". It's a story I tell each year that helps the kiddos understand what to do when we're doing double digit subtraction with regrouping.
Here is the poster I make with the kiddos to go along with the explanation....
Here's the Story:
"'You' are in the top right apartment and you want to give something special to your downstairs neighbor. The only problem is since you're a smaller number than your downstairs neighbor, you don't have enough money. You need to borrow 10.
You always always always borrow from your upstairs neighbor because he's so nice and will always lend you a ten. You NEVER borrow from the downstairs neighbor. He's a grouch--probably because he has to live on the ground floor and doesn't like it.
Once you've borrowed your ten, make sure your upstairs neighbor has 1 less and you have added "10" to yourself.
Now can you subtract?? Yes!"
I hope this strategy is able to help someone else out! The idea of giving each apartment it's own 'personality' has really given the kiddos something to visualize--making it so much easier for them to remember. Let me know if it works for you too! :)