The superintendent of a North Carolina school system says a high school teacher is being investigated after students say he stepped on an American flag as part of a history lesson.

News media outlets report a photo posted on Facebook shows history teacher Lee Francis standing over an American flag in front of a class at Massey Hill Classical High School in Fayetteville on Tuesday. Students were quoted as saying Francis asked students for a lighter or scissors, and when no one produced them, he put the flag on the floor and stomped on it.

The news reports quote Francis as saying on his Facebook page that the lesson was about a legal case which upholds that flag desecration is protected by the First Amendment and the Bill of Rights.