Cathy, did you skip your DS out of K or after K? Did he go right to second grade? I've heard good things about the Singapore Math books, I think I will look into them. I'm always worried that we're missing something in her math learning.
Hi, Dawn--
Well, it's a little complicated... he was in a private PreK and they decided to move him into their K program when he turned 4 (he has a November birthday). That didn't go too well, because it turned out that the K teacher didn't really want him there

He finished out the year in that private K program, though.
The next year, we enrolled him in K again at the public school. He was already reading at a third grade level and doing addition, subtraction, multiplication, counting past 100, etc. After a couple of months of him becoming less and less engaged at school (he would just sit there and daydream) and no sign of him making friends with the other kids, we talked to the school about differentiated instruction. They had a hard time fitting that in. Then we asked about subject acceleration. Too complicated for them to schedule. Finally, we asked about a gradeskip. I pointed out that it would be the easiest way for them to give him more advanced work. They recommended having him do the K class in the morning and then joining the 1st grade class after lunch. He did that for a few weeks, and all seemed well in first grade so we moved him up to first grade midyear.
I have found that schools are more willing to listen to you if they get to know your child for a month or two before you start advocating for different work. It is frustrating to wait, though! We were lucky that there was an opening in first grade. You could ask for your child to try first grade in the afternoon when a space opens up...