8 months ago
Last edited at 12:41PM on 4/10/2013
Almost all K-12 schools in the US require one to have a Masters Degree, you can potentially start teaching in some capacity with a Bachelors, but you would still have to be working on getting your Masters at the same time. So at the very least you are looking at 4, plus an additional 2 or so depending on how long it takes you to complete your course work.
If you are looking at teaching at a college level, then you would probably need to work on your PhD as well.