There are several examples of positive student-led revolutions. In the Velvet Revolution in Czechoslovakia, the student-led protest organizations were the driving force for change. [1]

The mass protests that toppled the military regime in South Korea in 1987 was also led in large part by students and faculty members, who later became prominent leaders. [2]

This has also happened twice in Serbia now. Milošević was defeated in 2000 thanks in large part to Otpor, a student-led organization [2].

[1] http://news.bbc.co.uk/2/hi/8363827.stm

[2] https://en.wikipedia.org/wiki/June_Democratic_Struggle#Stude...

[3] https://www.wilsoncenter.org/event/bringing-down-dictator#1