If you want to teach in public schools at least. I think private schools might be different. My wife had to take classes every month for a few months to get her alternative teaching license, because she didn't have a degree in education. However, she wanted to teach elementary school, and it may be easier to qualify to teach older students.
Private school may be different. They have different regulations, and more leeway in their hiring practices.
Where do you want to teach? Rural? urban? rich? poor? public? private?