Why might a dictatorship focus their attack on students, teachers and professors?

For your first question. Well, knowledge is power. May sound like a joke, but its true. If you don't know about a threat, you can't prepare you self for it. And even if you know of the threat, you still have to know how to prepare for it. Well, teachers are generally educated individuals. And educated indivuals are usually the ones that speak up against governments. Remember vietnam? It was teachers, but mostly students that were protesting.Students are usually seen as threats because there young and filled with various ideas. The government targets them because they are the future. And by brainwashing them, there brainwashing future generations with the same rederic. On your second question. Well, they ban political parties so there is no political opposition. And dictatorships don't ban newspapers, they just take them over. Then use them as propaganda outlets for the people. Control the media, you control what the people think. Divide and conquer.