But now, 20 years on, modern technology and the wide reach of social networking sites like Facebook are providing curious students with the information they were previously denied.
"In this, 20 years ago, China strove for democracy and freedom. The government killed our compatriots, university students and citizens," wrote a woman identifying herself as Bonnie Wong on the Facebook fan site Tank Man, one of several forums that have popped up ahead of the 20th anniversary of the crackdown.
"For 20 years, more than a few have entered the political arena who are the real villains, hypocrites who put on a false show of great peace and bury their consciences in a fiery pit. They control the government, they control media, they hold on to education, they control writing," wrote another Facebook member who calls himself Jonathan Siew.
The vast majority of Chinese youth show no outward knowledge of what happened 20 years ago, a fact that pains the still-mourning relatives of those who were killed.
"This is a cruel reality - young people do not know the truth," said Ding Zilin, a retired professor whose 17-year-old son was shot dead that night.
"The government hides the truth from children and keeps it as a sort of forbidden zone. It isn't taught in classrooms," he adds.
But in the anonymity of the online world, Internet-savvy youths use mirror sites and proxy servers to explore alternative versions of the official history and to discuss their own frustrations with their government's clumsy efforts at censorship.
China this week blocked access to Twitter, Bing.com, the photo-sharing Web site Flickr and, briefly, Hotmail. Other sites, including YouTube and blog providers like Blogspot and Wordpress, are routinely barred.
But frequent Twittering and Facebooking from Chinese users on the eve of the Jun 4 anniversary proved there are many ways around the censors' efforts.