P.S. I just re-read your thread and am still unsure whether you are debating K12 vs tiered programme and whether both are for teaching schoolchildren.

This brought up a third comment for me, which that if teaching schoolchildren is your chosen career path, then I would look less at the short-term cost and more at what will make you secure and give you a good status in your workplace ten/ twenty years from now. Because when you become a 45 or 50 year old school teacher you will want to be up there with good grading, good pension prospects and an equal status to your peers re opportunities. I have friends who are coming up to retirement age as teachers (lucky them) and who have survived many education system changes, and the opportunities open to them as a result of their licensure status have been more important than short-term costs.

Just my point of view .