Friendly Numbers But Not



November 4, 2019

Friendly Numbers But Not!

The following NT with preservice teachers included the following clusters:
  • 999 +99
  • 998 + 49
  • 199 + 99 + 49
999 + 99 is 1098.
Me: How did you get 1098? Explain your thinking?
Katherine: I added 1 to 999 to make 1000 and took 1 from 99 to make 98. 
1000+ 98 equals to 1098. 
All three seemed to have the same idea.

998 + 49 is 1047
Me: How did you get 1047?  Explain your thinking.
Chase: I separated  998 to make 990 +8 and 49 to make 40 + 9.
Then I added 990 +40 which equals to 1030 and 8+9 equal 17.
1030 +17 equals 1047.
Katherine: I just did like I did before but I took 2 from 49
and added it to 998. 998+2 equals 1000. 49-2 equals 47. 1000+47= 
1047.

199 +99 + 49 is 347
Katherine: I took 2 from 49 and added it to 199 and 99.
199+1 is 200 and 99+1 is 100. 200 +100 equals to 300+ 47. 347
Erika: 199 +1 is 200
            99 +1 is 100 
           49-2 is 47
            200+100 +47 is 347. 
Discussion
This NT is similar to the previous weeks. However, PT willingness to use different strategies and add flexibly have improved. No-one attempted to line up the digits and air add. They used strategies such as compensation and place value to add numbers. Chase even bordered on using the associative property. 
I consider NT a daily ritual. However, we do more than NT in math methods. I am emerging PT in counting collections as well. 
I hate that this class is offered once a year. I have to squeeze so much into a busy semester. It's hard to cover PreK-6 grade. 

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