I do not think there are any specific classes you need to take in high school to be a theatre arts or visual arts teacher, but you may consider taking visual art classes and/or theatre arts classes. Generally, one cannot be a teacher of both unless you are qualified. When in college, you would need to pursue a double major in art and theatre and get a teaching certification. I am not certain about what your situation will be in college, but some colleges require you to take a certain number of classes more than the individual degree to get the certification. You may also consider double majoring in art education and theatre education. The classes focusing on education will overlap for the two degrees.