Subtraction By Chunking
Published on Nov 19, 2015
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MORE DECKS TO EXPLORE
PRESENTATION OUTLINE
FIND THE DIFFERENCE.
IN THEIR AGES.
The DIFFERENCE is the answer to a subtraction problem.
We can find the difference by subtraction with renaming or by adding on.
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COUNT ON
FROM
Let's do some mental math. We will count on starting at the subtrahend, 28.
Remember these vocabulary words: minuend, subtrahend, and difference.
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STOP AT
64 IS THE MINUEND.
The minuend minus the subtrahend results in the difference.
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SUBTRACT BY
ADDING ON, JUMPS ON NUMBER LINE
Let's pretend that we are jumping on a number line. Start at the number 28. How far do you have to travel to get to 64?
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FIRST, A TINY JUMP
FROM 28 TO 30.
There is more than one way to make your jumps.
This little froggy starts with a tiny jump. But he could have started with a big jump.
Where would the frog land if he started with a jump of 10?
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NEXT,
ONE BIG JUMP FROM 30 TO 60
This is quite a BIG jump. Could the frog make smaller jumps from 30 to 60?
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CALL EACH JUMP A CHUNK
ADD CHUNKS: 2 + 30 + 4 = 36
Now, add up the length of each jump. The result is the difference between the two numbers.
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REVIEW STEPS
- Jump 2 to 30.
- Jump 30 to 60.
- Jump 4 to 64.
There were two small jumps and one big jump.
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ADD CHUNKS
This is how your jumps might look on paper.
Locate the starting point, subtrahend. Locate the ending point, the minuend.
