Yes, it is sad but true. I have heard plenty of stories about homophobic remarks being made in the class room and resulting in no correction by the teachers. This article by Deb Price in the Detroit News, describes a story where the remarks are actually coming for the teacher. Ubsurd!! and completely unacceptable. She goes on the discuss a report called "Shared Differences" done by the Gay, Lesbian and Straight Education Network examining what the school environment feels like for America's LGBT minority youth.
You should read the article.