Do you teach divisibility rules, prime and composite numbers, GCF and LCM even though those standards don't seem to appear until 6th grade? I feel like it is so important for students to better understand computation of fractions. It takes a good chunk of time to teach it. Thoughts?

Yes, I do teach these in 5th grade. I do so because I agree with it, and we (it was a group decision) decided to still teach these in 5th grade even when we chose to use Common Core.

I'm going to teach, though not stress the wording/vocabulary, of finding the LCM sometime in the next few days in order to help my fourth graders compare/order fractions by finding equivalent fractions with same denominators. And prime/composite was taught earlier this year, too. I think many of the concepts, even if not part of the standards yet, are hinted at and perhaps not fully formalized, which helps them to formalize it when it does become standard.

This is my problem, because it's hinted at that it's known already, but yet not taught (in my experience).

When I did my student teaching in 6th grade math, we went over LCM and GFC and students said they "knew it" already. But they had a hard time with it. I think introducing it earlier would be great. But you don't want to teach something that another grade will teach. But it definitely does help.

I get that these are 6th grade standards, but I find it so difficult to teach adding and subtracting unlike denominators and telling my students to find a common denominator without reviewing LCM/LCD. BTW - 2 weeks until PARCC and I haven't taught fractions!

GCF and LCM are actually included in our curriculum, so we do teach them. (Though the kids need more reinforcement than the book seems to think they do....per usual...) 2 weeks?! Why is your testing so early?? Ours isn't until April and I'm still irritated by how early that is! How are you supposed to teach an entire year of math by February?