Alrighty, I’m getting back to this now that our school year is over and I can think again. Thanks for the comments and questions so far; they’ve helped steer my thinking in the right direction. I’ve done some research, and I’m starting to make sense of 3rd edition vs. 4th edition and Intermediate 3 etc. vs. Math 3 etc. This page was especially helpful.
So what are the pros and cons of using Intermediate 3, 4, and 5 vs. Math 3, 5/4, and 6/5? For high school I’d lean towards using the 4th edition so students could get their geometry without necessarily taking Algebra 2 and Advanced Math. Are there advantages to the 3rd edition that we should consider?