Dr. Beth McCulloch Vinson

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Dr. Beth McCulloch Vinson Athens State University

PT3 Grant Funding, Summer 2000
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Subtraction We s
ubtract when we want to find the amount that we
have left when we take away.
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Subtraction We also
subtract when we compare the difference between
two sets.
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Lets do a take away problem.
3 balls take away 1 ball leaves us with 2 balls
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Lets do another take away problem.
5 balls take away 2 balls leaves us with 3 balls
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Lets do a compare the difference
problem.
There are 5 blue balls and 3 red balls. What is
the difference between the 2 sets?
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We solve this compare the difference problem by
subtracting. 5 take away 3 equals 2. The
difference between 5 and 3 is 2.
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Lets do another compare the difference
problem.
There are 6 blue balls and 2 red balls. What is
the difference between the 2 sets?
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We solve this compare the difference problem by
subtracting. 6 take away 2 equals 4. The
difference between 6 and 2 is 4.
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A Project Developed for Preparing Tomorrows Teac
hers to Use Technology (PT3) By Dr. Beth McCulloc
h Vinson Athens State University, School of Educa
tion http//www.athens.edu/vinsobm