Hi Val,
For elementary math, besides division, there should be several other topics. The middle school math teacher I know says incoming kids are typically weakest in decimals, percentages, fractions. Ratios too. Algebra topics can be introduced early (my second grader is also doing some work in class), though it's an introduction. I like the idea of introducing math-talented kids to advanced topics to pique their interest and give them broader knowledge.
My son seemed ready for Algebra early and I worked him a little, because the school did not want to advance to beyong pre-Algebra. It benefitted him to review concepts he reviewed early (and forgot). It was frustrating that no one was/is willing to teach a young-ish kid advanced topics, but I do think there is a maturity required for multistep operations. Definitely introduce him to topics, but expect him to need a deeper understanding before mastery.
Just my opinion...
