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Friday, February 9, 2018

Headfirst 3 - Decomposing Numbers to Make a 10 when adding to 7, 8, and 9



Hello! It's February and we are learning about regrouping by decomposing numbers to make a 10 when adding. Sounds complicated? It can be. What's the point? To teach kids about making a 10 which is perhaps the most important concept in our base 10 system! To teach this, I used the Headfirst Math Curriculum Unit 3: Making a 10 to add using numerals and number bonds.

This is what it looks like:

Adults do this regrouping in our heads. Kids, however, need more concrete learning. It is important to review the ways to make 10 before and during this unit (end of unit 1).

Also, kids need to practice 10 + single digit facts. They will eventually do this in their heads. (Unit 3)


This student is working on 5 + 9. He was having trouble so I pulled out some manipulatives to help him understand the process. We started with 5 yellow and 9 red. Then we moved one of the yellow hearts to the red pile to make a 10. Here he is counting the other part of 5 which is 4.


By this time we were doing the 10 + 4 in our heads. 

One thing I will do differently next time is that I will mix up the 9 + facts from the beginning. They got used to seeing the same numbers in the number bond as in the answer and it isn't 11, it is the parts of 2. 

Mixing them up from the beginning should eliminate them getting into this habit. Here the 5 comes first because  I wanted the 1 close to the 9 to lasso it into a 10.


After working on 9 + facts. We moved to 8 + facts.


And finally 9, 8, and 7 + facts.

At the end of the week, I put the students in two teams on the carpet. I wrote a problem on my whiteboard and they each worked it on their whiteboards. It was nice to see them helping each other with all the steps. After a couple minutes, I said markers closed and they showed me their work. I counted to see which team had the most correct and awarded that team a point. They really enjoyed it and helped each other. At the end, it was 4 to 1 so one team clearly had the concept better than the other. I sent the winning team back to their seats to do the worksheet alone while I completed it together on the carpet with the losing team. We worked on this concept for a total of 2 weeks.

I am hopeful for the test tomorrow!




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