Thousands of students at the University of Tehran gathered to demonstrate against the regime and commemorate the "Students' Day". As you can see in the above pictures the main theme of their gathering is to demand "Democracy" and an end to the sexual segregation at schools:
"A lot of protests were directed at Ahmadinejad over oppression in universities and the bad economy," he added. "The protesters also demanded academic freedom and respect for human rights."
More photos are here and here! al-Reuters has another report on this gathering too where it calls these students "an illegal splinter group" of students. Shame on al-Reuters.