Mario Van Peebles tries awfully hard to disguise the heavy-handed messages he has ladled into “We the Party,” a high school movie that he wrote and directed and filled with his relatives. Teenagers these days, though, are pretty sophisticated when it comes to being manipulated. And anyway, they’ve been hearing these same messages — study hard; don’t judge people by appearances; there’s more to life than bling — for years on the Disney Channel. The film focuses on a group of friends at a multiracial high school as they learn the usual lessons via plotlines and scenes that have been beaten to death by other movies and television shows. There’s a lose-your-virginity contest. There’s a big party where life-changing moments happen. There’s a looming prom. Mr. Van Peebles gives himself the role of energetic, inspiration-spewing teacher. (“If you want to go out in the world and do something big, teach a child to read, invent a clean-energy source, sacrifice for others.”) His real-life son Mandela plays his fictional son, who is also one of his students. Other Van Peebleses also populate the movie, and all are serviceable enough as actors; it would be nice to see them in less earnest, more original material. “We the Party” is rated R (Under 17 requires accompanying parent or adult guardian). It has vulgarities and sexual themes.