Protests against changes in France’s higher-education system gathered momentum today, with lecturers on strike and demonstrators taking to the streets in some 20 university cities throughout the country, The Guardian and other news sources reported.

Protesters clashed with the police in Strasbourg, where the higher-education minister, Valérie Pécresse, was visiting and a large number of students and lecturers had gathered. Organizers estimated the crowd at 2,500; the police put it at 1,600. Some of the demonstrators “started throwing objects at the police, who responded by firing tear gas at the protesters,” Reuters reported.

The unrest halted classes at the University of Strasbourg, and several other institutions around the country have also faced disruptions by a strike that began on Monday. Groups representing students and lecturers say that teaching has been disrupted at nearly half of the country’s universities, and are calling for protesters to converge on Paris on Tuesday in a national day of action.

The demonstrators are unhappy with a raft of changes the French government has introduced, including recently announced proposals to give university presidents authority over how researchers who teach divide their time between research and teaching. —Aisha Labi