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Monday, October 28, 2013

Composing and decomposing numbers

What does it mean to compose and decompose numbers?   If you compose a number you out it together.  If you decompose a number you break it apart. Our  math standards state we can compose and decompose numbers 11-19.  Students must see one of these numbers as 10 and some more.  For example, the number 14 is 10 and 4 more. We would write that number sentence as 10+4=14. 
This week I am giving the students a 9 domino (has numbers 0-9 on each side). They must reproduce the dice on their paper and count to decide how many.  When they come up with the answer and wrote it on paper correctly (14 is written with a 1 and a 4 (14) not a 4 and a 1 (41) ) then they have composed the number.  They then have to represent the number in place value (1 rod and 4 ones) and wrote a number sentence to match.  




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