Campus protest or student protest is a form of student activism that takes the form of protest at university campuses. Such protests encompass a wide range of activities that indicate student dissatisfaction with a given political or academics issue and mobilization to communicate this dissatisfaction to the authorities (university or civil or both) and society in general and hopefully remedy the problem. Protest forms include but are not limited to: sit-ins, occupations of university offices or buildings, strikes etc. More extreme forms include suicide such as the case of Jan Palach's, and Jan Zajíc's protests against the end of the Prague Spring and Kostas Georgakis' protest against the Greek junta of 1967–1974. In the West, student protests such as strikes date to the early days of universities in the Middle Ages, with some of the earliest being the University of Oxford strike of 1209, and the University of Paris strike of 1229, which lasted two years. More widespread student demonstrations occurred in 19th century Europe, for example in Imperial Russia. In 1930s, some Polish students protested against anti-Semitic ghetto benches legislation. In the second half of the 20th century, significant demonstrations almost-simultaneously in many countries: the May 68 events in France began as a series of student strikes; Polish political crisis that occurred the same year also saw a major student activism; and the Mexican Movement of 1968 also started with students. The largest student strike in the history of the United States occurred in May and June 1970, in the aftermath of the American invasion of Cambodia and the killings of student protesters at Kent State University in Ohio. An estimated four million students at more than 450 universities, colleges and high schools participated in what became known as the Student strike of 1970. It has been argued that student strikes and activism have a similarly long history in Confucian Asia.