Last week, we began Chapter 9, “Add Numbers Within 1,000.” We used the strategy of Compensation to add and subtract 3-digit numbers.  

You can view this video for an explanation of using compensation to add 3-digit numbers. You can view this video for an explanation of using compensation to subtract 3-digit numbers. 

This week, students will use the strategy of “Partial Sums” to add 3-digit numbers. You can view this video for an explanation of using partial sums to add 3-digit numbers. Then we will move on to using the strategies of regrouping to add and subtract 3-digit numbers. Remember, this is the strategy that most of us adults were taught. It used to be called carrying (for adding) and borrowing (for subtracting).