## Friday, November 30, 2012

### Subtracting by Counting UP!

I find it amusing that even though we are already into our 64th day of school some of my student don't know what to do with the signs +, -. Well actually they do know what to do with those signs but the indecision on which one to use is complex in some of their minds. I began using the Subtracting by Counting Up strategy.
This is an amazingly powerful way to subtract. Van de Walle in his book "Teaching Student Centered Mathematics" explains it as students working on the think addition strategy for their basic facts can also be solving problems with larger numbers. The concept is the same. It is important to use join with change unknown problems or missing-part problems to encourage the counting-up strategy he explained.
I have noticed that although we have done many 2.OA.1 word problems that when I use the terminalogy "how many fewer did Jack have than Bob" or when I use a problem like Korryn has 9 dolls and Kate has 3 more dolls than Korryn. How many dolls does Kate have? My students come up with some amazing ways to solve this word problem. Many got it right on target but many were more than a little confused.
I have begun to use the subtracting by counting up strategy and I hope on next weeks summative assessment I will see more students "get it". Does anyone else have this sort of problem when adding words or creating a word problem. They can actually add 9 + 3 = 12 but it seems with the CCSS terminology they get confused. I have been adding one to three of these each week and hopefully next week I won't have to omit it. YIKES!

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