GCF and LCM

Does anyone have any tricks to help students tell the difference between the 2? My fifth graders are constantly getting the two confused!

Re: GCF and LCM

I haven't had too much trouble with them getting it confused. I always teach multiples FIRST. we skip count and use the hundreds charts to find multiples. i also point out the word MULTIPLE is like MULTIPLy so that a multiple of a number is multiplying by (2, 3, 4, etc. ) So for example, 9 would be a multiple of 3 because 3 x3 is 9.

I also have a great game called "multiple turn-overs."... I can FM it to you.


For GCF's, i teach it by creating factor trees, which i'm sure you have seen. i teach them that a math FACT contains the FACTors.... so for example, 4 x 6 = 24 so 4 and 6 are factors of 24.

Showing them the relationshiop between the actual words and the concepts really helps my kids as well as the visual in the word. when they think the word multiply they see it's a multiple and that the numbers in a math FACT are a FACTor.

Does this help or did i confuse you more?

Message edited 3/30/2008 12:58:03 PM.

Re: GCF and LCM

Thanks! I like the facts and factors connection! I'll have to try that. I just think there's too many acronyms with fractions - they get uber confused!