It honestly depends on where you want to teach -- in the US, some states require a Masters Degree, other states, a BS/BA are all that's necessary. Plus you'd also need some teaching certifications.
I've actually thought about doing this - but I doin't have the time nor money (nor brains) to get a Masters in Math (which is what I would want to teach)
this site will give you a link to the requirements to teach in each of the 50 states.
http://www.uky.edu/Education/TEP/usacert.html
Teaching is a lot of bureacracy, a lot of politics, low pay, not as much respect as you should get, but it's an incredibly noble profession and there is such a shortage of good teachers, and you will make a difference in peoples lives.