Why do teenagers in high school appear taller in the movies and on TV than in real life ?

Do you mean they appear talked than current high schoolers? Or taller than that same air looks in real life on the red carpet?

A, because most actors playing teens are older (19 - early 20s...yes you keep growing a bit)

B, while acting is more lenient, it's still similar to modeling, where, if given the choice, taller people are favored.

C, they go out of their way to make them look taller, because for some reason, industries have height labeled as a major part of attractiveness (I disagree) so they use camera angles, smaller sets, and graphics to make them appear even taller.

Directors use low camera angles to make the actors appear taller.

They especially do this with men to make them look taller and more dominant.

They would tend to use higher camera angles for women to make them look smaller and dainty.

Also, actors in TV shows or movies about high school are usually 20+ years old.

Because thats what they want you to think. They just make the cameras a little lower, so the people seem taller than they really are. In reality, the actors are probably shorter than most people.

Because the actors are 18+ in movies.

I actually think they seen shorter... :/