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Saturday, March 8, 2014

Math Subtraction strategies

This week we are learning about subtraction. 

When were suppose to so one strategy at a time but they would have none of it!  "We want to do all our strategies!"
Ok- I'm flexible...so I rolled with it. 

I made this sheet for our journals so we could focus more on completing our strategy and not drawing it. 

For example:
Kelly had 8 crayons.  She let her friend Rachael borrow 5 of them.  How many crayons does Kelly have now?

We begin with deciding- Do we know the whole and some go away? Or Do we know the two parts?

Well with subtraction, we know the whole so we put the greatest number in the whole section of our organizer. 
Then we put in our known part and wrote a question mark in the part that is unknown.  

Now we can write our equation and answer sentence.  

Then we choose our strategy.  
For the tens frame we put the whole amount in and mark out the part we know.  What is left is the answer.   

When we make our number line, we always start with the greatest number and jump backward. (I like to put the correct number of dots and the fill in the numbers to make sure the kids "jump" the correct spaces)

The unit bar and number bond gets tricky.  
The whole is in the circle that is by itself and then we put the part we know in the one of the other circles and a question mark in the other.  
We draw the whole and then mark out the part that known. The remaining part is the answer.  

Now we go back and fill in our graphic organizer, equation, and answer sentence. 

I hope this helps.  Please let me know if you have any questions.  

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