Zaccaro books are good as well - Primary Grade Challenge Math.

Forging ahead w/ SM has it's risks. Ask me how I know. On the one hand, you're feeding their interest...on the other hand you're only making the divide wider w/ the classroom. There's no easy answer.

I moved into othe arenas with my son...chemistry and physics and history...but of course that is making problems in those areas later on...delaying the problem.