To get a teaching degree, you'll have to enroll in a college or university that has a school of education. Most academic institutions require that you attach an education discipline to a degree that covers a broader subject, such as English, history, or math. Thus, you might get a bachelor of arts in English with a concentration in education. Under this system, you'll take education classes alongside classes that fit in with your chosen major. Some universities also allow you to get a bachelor's degree in education without having to choose another major.
One of the last semesters of your schooling normally will be devoted to student teaching, during which you'll be paired up with a local K-12 school to gain some field experience. Finally, before you graduate, you'll have to take a teacher certification exam that's accepted by the jurisdiction in which you reside. If you pass the exam, you'll be able to graduate with full licensure to teach in the jurisdiction in which you attended college.
When you decide on what major to choose for your teaching degree, keep in mind that whichever major you choose may well pigeonhole what kinds of courses you'll be allowed to teach during your career as an educator. For example, if you choose a math major, but also wish to teach history, you might find that prospective employers only wish to look at you as a math teacher. To cover your bases, you might choose two majors that interest you as potential subjects to teach — in this example, you could double major in history and math. You could also major in one subject and minor in another. Of course, many schools might be quite flexible about what courses they’ll allow you to teach, so long as you demonstrate that you have a proficient understanding of the given subject.
There is an important distinction between getting your bachelor's degree and getting your teaching certification; the two can be obtained separately. If, for example, you've already obtained a bachelor's degree and now wish to obtain a teaching degree, you may be able to save yourself the trouble of enrolling in a university again. Alternate certification programs are offered in many jurisdictions that allow postgraduates to officially train and study for teachers’ licenses. Some alternate programs even offer paid teaching jobs for those who complete certification programs and obtain their teaching degrees.
Some private schools don't require their teachers to have a teaching degree or license. Most private schools do, however, require that their teachers have at least a bachelor's degree in some subject. Even those who plan on teaching in private schools may be wise to obtain their licensure; teaching is a competitive field, and the more certified and educated you are, the more you may be able to distinguish yourself from others when competing for a job.