Tuesday, February 18, 2014

Subtracting Across Zero and a Giveaway!

My students have been getting pretty darn good at using regrouping to subtract. I only had to ask "more on the top or more on the floor?" about 7,000 times! One thing they are stumbling on is what to do when they encounter a zero when they "go next door" to regroup. It is now time to drag out the Boxing In (or Squaring Off) strategy I learned last year. I found this YouTube video that explains it better than I ever could:
click here to take you to the video
I show this video to my class SEVERAL times so they can get the hang of it. It is a very short video, but the best part is watching the student do an example at the end. I think this really shows the kids that they can do it! To give the kids some extra practice in a fun way, I made this set of task cards with QR codes:
click here to get it
Each card has a 3-digit subtraction problem in which there is a zero "next door" when you are regrouping. I added QR codes so students can get immediate feedback about their work. 

I usually use these types of task cards as a math center. In this case, I'm going to break it into two stations because it is a relatively new skill. I will probably bring this out later in the year as review and make it one station when they become more fluent.

For some reason, this technique makes so much sense to my kiddos. Here is an example:
I hope this helps take the frustration out of teaching subtraction with regrouping across a zero. I'd love to hear how you teach kids to use regrouping to subtract! I'll pick one comment at random to receive this product for free.

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