For many years, American colleges and universities have let people speak on their campuses even if many students do not agree with their beliefs. College-aged students often do not agree with conservative political beliefs. But school officials believe that letting speeches by conservatives and others take place on campus can help lead to free and open debate. But recent protests show that beliefs about free speech on college campuses may be changing. Since February, protests have broken out at colleges across the country -- including the University of California-Berkeley, Middlebury College, the Claremont Colleges, and California State University, Los Angeles. Some of the protests turned violent. The protests started because conservative speakers were set to give talks about their beliefs. Some people have criticized the protesters for trying to prevent controversial speakers from being heard.