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catapult catapult is offline
 
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catapult
 
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Gcf
Old 01-24-2013, 09:24 PM
 
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any ideas for how to teach GCF... I have never taught it yet- and I want my kids to understand it well... (also how do I explain to my students what factors are- in a clear way?)


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fraffert fraffert is offline
 
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GCF and LCM
Old 01-26-2013, 09:06 AM
 
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My 5th graders have always had a hard time keeping LCM and GCF straight. I found this PP online somewhere, probably on here. My kids have really got it this time. I will inbox you, since I can't post it because I didn't create it myself. Hope it helps
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T charts
Old 01-26-2013, 09:12 AM
 
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I have mine make t charts to list all of the factors to find the gcf.


I remind mine that FACTORS are the numbers used in your basic FACTS

MULTIPLES are the answers after you MULTIPLY.
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SusanTeach SusanTeach is offline
 
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factors
Old 01-26-2013, 09:20 AM
 
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One way that I still remember it (and taught it with 5th graders) is that Factors are "Fewer" and Multiples are "More". It's a simple thing that helps them remember when asked to give the factors or multiples - they know what to look for.

Example:
Factors of 25 (fewer than 25): 1, 5, 25
Multiples of 25 (more than 25): 25, 50, 75, 100, ....
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Old 01-26-2013, 03:11 PM
 
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When I am actually teaching them how to find the GCF (after they are clear what factors are) I have them list all of the factors for each number in the fraction right there on the fraction.

2 -1, 2
6 -1, 2, 3, 6

Then, they circle the ones that are common. The largest number circled is the GCF and then is the number to be divided with. (I wrote a blog post with pictures that explains it a bit better here....can't post a bunch of pics on PT, so I just linked the post.)


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catapult catapult is offline
 
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Thank you all so much!
Old 01-26-2013, 07:09 PM
 
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I am going to be teaching it on monday! hope they get it... with all of your good ideas- im sure they will!!
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T Chart
Old 02-26-2013, 11:21 AM
 
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I also use a T chart. On the factors side we write....FACTORS ARE FACTS, THEY ARE THE "INS" (THE NUMBERS ON THE INSIDE OF THE = SIGN.), MUST BE LESS THAN OR EQUAL TO THE #

MULTIPLES ARE THE "OUTS" (THE # ON THE OUTSIDE OF THE = SIGN, THE #S YOU GET WHEN YOU SKIP COUNT, MUST BE GREATER THAN OR= TO THE #
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