this has been a really neat thread to read...we have been concerned with the same thing with our DS5 on a much lesser degree than the original post though. There were NO exceptions in our area for any kind of acceleration or differentiated instruction for an advanced kindergartener...so we began homeschooling this year for kindergarten- here we are several months into it and he is complaining that the end of First grade Singapore math is too easy and he's reading on an almost 3rd grade level....so I am attempting to figure out his true level of work but it has been a very exciting to watch him and allow him to explore whatever topics interest him. We were also concerned about how in the world would he go back into public school because he is so out of whack concerning grade levels.
