Hi,
Too bad you just missed the 40% off sale on K12. I think there's still a 10% discount, but not sure.
Last year in K12, DS was in LA4, History and Art 5 (they're connected); music 3, Math 4 and then 5, and Science 7. That's what I liked about it. What was tough is that they won't divide up the Language Arts strand. I needed DS in 3rd for writing, 5th for reading, 4th for spelling, >6 for grammar and vocabulary. I ended up going with 4th b/c the mismatch for writing would have been too great with the other levels. However, the fact that grammar and vocabulary were so easy made it easy to get his cooperation for writing in the workbooks. At least he was writing words, and in history and science he'd write sentences. I never compared prices with the other curricula you mention.
oh - and most importantly, we're independent. Not sure you could mix and match as much in a virtual academy (and it appears you don't have that choice anyway). HTH. Good luck!
