A successful component of a college credit art history class at McCracken County High School in Paducah, Kentucky has been cancelled because of a controversy provoked by an art installation involving the United States flag. The furor over what was simply a students' recreation of a 1989 piece by Dread Scott raises grave questions about the extent to which schools can, do or should censor educational assignments in fear of political pressure.

To engage her students in a reading about the history of art, a teacher set various assignments for which one option was to exhibit a restaging of an artwork accompanied by an infographic. The students chose that last option and recreated one of Jasper Johns' flag pieces, a work featuring the flag by Faith Ringgold, and Scott's "What is the Proper Way to Display a US Flag?"

All of these works were, at some point, controversial, but the showdown at McCracken focused on the Dread Scott piece: this was an audience-participation installation that features a montage of images of flag-draped coffins and South Korean students burning US flags, a response book, and a flag laid on the ground. Audience members are given the choice of stepping or not stepping on the flag as they write in the response book.

For the 30 minutes the Dread Scott restaging was on display in the school hallway, the students in the class responded to questions and engaged their peers in a lively discussion. Soon after, however, the assistant principal, accompanied by a student, removed the flag, thus dismantling the installation.

After the incident was reported in the press, the ensuing hate-filled furor in mainstream and social media led the school and the teacher concerned to issue apologies. Any future repetition of the assignment has been cancelled. In future, teachers offering similar, potentially "offensive" assignments will have to seek permission from the school administration.

The stars-and-stripes is probably the most emotionally loaded symbol in the US – even if the emotions it stirs are often contrary. American soldiers raised it in triumph over Iwo Jima at the end of the second world war, while Vietnam war protesters burned it in disgust at the military actions of the US government. More recently, the flag is reverentially draped on the coffins of US soldiers killed fighting America's increasingly unpopular wars – and the stars-and-stripes continues to be used by artists to condemn those wars.

Repeated congressional attempts to ban flag desecration have been invalidated by the US supreme court because the symbolic act of burning the flag has been ruled a type of expression protected by the first amendment. Indeed, some of the supreme court's most eloquent words in defense of free speech have been written in cases involving the flag: in 1943, while striking down a law requiring schoolchildren to salute the flag, the court ruled:

Freedom to differ is not limited to things that do not matter much. That would be a mere shadow of freedom. The test of its substance is the right to differ as to things that touch the heart of the existing order.

Yet, today, polls show about half the nation consistently supports a ban on flag-burning. And it is a vocal half.

The first amendment may offer legal protections to politically controversial speech, but it does not generally protect a teacher or a school from the onslaught of public outrage. And we've seen in other fields how the fight over the hearts and minds of the young generation has become one of the most heated political battles in the US – witness the debates over the teaching of evolution and "intelligent design", over sex education, over the history curriculum and so on. Fearing for her job, a teacher may well decide to offer her students a blander diet rather than face a vituperative backlash.

The pressure on schools and teachers to censor themselves and their curriculum – and to eliminate engaging assignments just because they may touch on politically sensitive topics – hurts young people and their education. An education that feeds students unquestioning patriotism – or, for that matter, unquestioning anything – and squelches any initiative they may take to explore controversial issues is not likely to produce free-thinking, independent-minded citizens.

In a contradiction that seems entirely lost on them, those who threaten a teacher because of a fetish over a piece of cloth appear to have no problem trampling all over the very principle of freedom the flag is supposed to symbolize.