Double-Digit Subtraction

The students have been working hard this week with double-digit subtraction with and without regrouping. We know how to borrow from the tens place to get more ones for subtracting. This is the poem we use to determine if borrowing is necessary. 

 

And it's been a fun week of lessons.

On Monday, Mr. Cavileer made a bunch of mistakes with his borrowing and the students had to find where I went wrong.  Did I borrow when I didn't need to?  Did I borrow incorrectly?  Or did I forget to borrow altogether?

 

On Tuesday, we were given 12 double-digit problems to cut into squares and sort.  4 of them had more on the top, so we knew there was no need to stop.  4 of them had more on the floor.  No problem.  We went next door to get 10 more.  The last 4 had the same numbers in the ones place, so zero was the game.

 

On Wednesday, we borrowed one of Mr. Scholder's gym games and put some numbers to it.  We played KaBoom with purple rectangles on the floor.  Half the tiles had double-digit problems to solve and the other half said KaBoom - Start Over.  It was a memorable, and sometimes frustrating, approach to getting from one side of the room to the other. 

 

Today, we wore our favorite dry erase vests and played Bingo.  There were 25 differences on a class Bingo board and every student was wearing a double-digit number.  When I picked two names out of the "It" jar, those students came to the front of the room and made a subtraction problem.  Sometimes their difference was one the Bingo board and sometimes it wasn't.  Sometimes we had to borrow and sometimes we didn't. 

 

Subtraction with borrowing is such an important skill for 2nd graders and it requires practice.  They can continue to hammer away at this standard here: