Pressed by police at every turn, Egypt's Islamists have turned universities into protest hubs to galvanise their flagging movement four months after a military coup toppled president Mohamed Morsi.
Morsi's loyalists have made no headway in trying to reinstate the jailed former president, but they continue almost daily protests nonetheless in a bid to force concessions from the military-appointed government.
"The coup authorities do not allow us to protest in the streets without cracking down," said Mahmud Sabry, a student at Al-Azhar University in Cairo.
"Universities are now our main battle front."
In Al-Azhar University, long seen as the highest seat of Sunni-Islamic learning, students have skirmished with police who fired tear gas from outside the university premises.
In another protest at the university, students stormed classrooms to force an end to studies under what they called "military rule".
The university is a short walk from Rabaa al-Adawiya square, which Morsi's supporters transformed into a vast protest camp for weeks before police unleashed a deadly August 14 crackdown on the sit-in.
More than 1,000 people, mostly Islamists, were killed in the police operation and ensuing clashes, and 2,000 Islamists have been arrested in an extensive crackdown on Morsi's Muslim Brotherhood movement.
Sabry said he wished he had been at the Rabaa al-Adawiya protest, but his father forbade him from going.
"Protesting at universities is a recompense," he says.
Since universities opened in September, students have held regular protests in campuses across the country, sometimes clashing with classmates who oppose Morsi.
On Sunday, hundreds of students protesting in Cairo University chanted "Morsi is my president" before scuffling with opponents inside the university as police and soldiers were stationed outside.
Clashes on campuses elsewhere have left dozens wounded, some by birdshot.
The unrest has angered students who, like a sizable portion of the population, despise the Islamists, and school authorities have tried to restrict the protests.
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"What the (Muslim) Brotherhood are doing in universities is terrorism. They provoke us into clashes then use violence against us" said one student at Cairo University, Sharif Harb.
The Supreme Council of Universities, which regulates state universities, issued guidelines banning students from protesting near classrooms.
The minister for higher education, Hossam Eissa, told reporters his government respected the right to peaceful protest. "But obstructing the educational process will not be tolerated," he warned.
History of campus action
Universities have been a haven for activists since a court decision banned guards belonging to the interior ministry from campuses in 2010.
Students played a leading role in overthrowing veteran strongman Hosni Mubarak in early 2011, and in mobilising protests that helped oust Morsi in July.
Some campuses, particularly Al-Azhar, had been bastions of support for the Muslim Brotherhood -- which has a long history of campus organising and student protests -- but as in much of the rest of the country, the tide has turned against the Islamists.
Despite the arrest of Morsi, his senior aides and much of the Brotherhood's top leadership, the group says it will persist in protests, hoping the rallies will attract ever larger numbers.
"Universities are a way to combine the energy of youths in one place," said Amr Adel, an organiser with the Brotherhood-led Anti-Coup Alliance.
But the crackdown on their top cadres, and the hostility of compatriots who often turn out to confront the Islamists at their demonstrations, have affected their ability to mobilise.
The Islamists say they are peaceful and that it is the police and civilian "thugs" who attack them. But they have not always shied away from confrontation.
On October 6, Islamist protesters tried to march on Cairo's Tahrir Square as the military and thousands of supporters commemorated the anniversary of Egypt and Syria's 1973 war with Israel.
Almost 60 people were killed in clashes with police around the country, most of them in Cairo.
The government has cited such violence to justify a state of emergency and a restrictive draft law regulating protests.
"The danger of what is happening in universities now is that maybe all student rights will be repressed, under the guise of confronting the Muslim Brotherhood," said American University in Cairo professor Ahmed Abd Rabou, blaming the Islamists' "violent approach".