We have been spending some time working on subtracting 2 numbers with 2 or more digits. This tends to be a difficult concepts to grasp right away so we will be practicing it from now until the end of the year. We use a little rhyme to help us remember what to do...
More on the top?
No need to stop.
More on the floor?
Go next door, get 10 more.
Numbers the same?
Zero's the game.
Another strategy that we use to help us with these problems is to draw out base-10 blocks. This helps the students visually see what they are doing when they borrow.