Thursday, April 14, 2016

Mental Math

We have been learning many mental math strategies for addition (and subtraction).

When adding we can:
  • Count all 
  • Count on
  • Use doubles or near douibles
  • Make a ten, then add  - 8+9 is (7+1)+9  which is 7 + (1+9)
  • Make a "friendly number" 23+48 is 23+50 then -2 (the friendly number is 50)
  • Compensate - manipulatint the numbers to make friendly numbers -- remove from one addend ant then add the same amount to another (48+12 is 50+10)
  • Breaking numbers into tens and ones -- then adding the ones, then the tens, and making new tens if necessary
When subtracting we can:
  • Count back
  • Add to subtract -- 14-7 What do you need to add to 7 to get to 14? then count on.
Let's see if we can put some of these strategies into practice and explain our thinking.

We are getting much better at using Mental Math Strategies AND showing our work -- and we can orally explain how we found solutions.!

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