What do I major in to become a secondary teacher?

There are two common paths for this career field. You can either major in secondary education from the beginning, meaning for your bachelors degree, with an area of study, i.e. math, english, science, etc.
If you plan on getting a masters degree, many people prefer to major in their area of study for their bachelors and then get a masters in education.

You will need an education major, grades 7-12 plus a major in a topic you are interested in teaching to students, Math, a world language, English, Science to name just a few. Most, if not all states require you to major or minor in the subject you wish to teach in order to obtain licensure.