Greve/Strike

There's something I've been wondering about...

Last Thursday there was a major "greve" or strike in France. A lot of the transportation was down and some places were closed in support. I understand that yes, the French feel the need to strike to show their voice. Thats fine. But students at schools can strike; university students. I'm just wondering how they get away with it. In the states if you were to strike at a college they would just fail you, so how can French students force a test to be moved, or decide they don't like how things are going and strike?

I realize this must come from the days of the revolution, but I still don't understand it.