In my own experience, you'll see teenagers who are more interested in politics when they're in their junior or senior year. This is probably because they've been so focused on college and grades that they have little time for current events. In fact, the only current events they know are probably through their classes.
Just because they sit in front of their computers all day does not mean that they do not understand what is going on. After all, the computer and internet is how we get most of our knowledge. Sites that are popular are also politically involved and are a fountain of information like Reddit and 4chan. So they know their news.
As far as their ideology goes, it is lacking. They may have 1 or 2 they have considered (namely Democrat and Republican) but that's it. They haven't really observed any other political ideologies to make an informed decision about what side to be on.