Students need to access school web sites which include links to book publishers and YouTube. There might be math videos on YouTube, but everything else is far more interesting. Video games get to be an enormous problem. Just having web access is enough to support a game addiction. Even something like Khan Academy or Scratch becomes a gaming platform, because programming is available and people have written games there.
Right now I'm relying on time-intensive and error-prone supervision. The computer is unlocked, observed while in use, and then locked. It's miserable for everybody. If the parent looks away, the gaming begins. Forgetting to lock the computer means that it will get used all night long, leaving the kid sleepy for the next day.