A better approach would be to invite a lesbian to the class to engage that student in a discussion in front of the class. It is much easier for bigots to sound off in a paper or online. But when faced with a human who is kind to you it's harder to spout off bigotry.
In the senior high school political science class I taught I devoted 10 or 15 minutes at the beginning of class on M-W-F to discussing current US political events. Students would be assigned in advance to present something of their choosing, and bring in some news item to read and prompt discussion that I moderated.
One day in 2004 a female student mentioned a gay marriage issue, I forget where or what it was. As I opened the class discussion this fundamentalist student jumped to his feet, without my first recognizing him, and literally started thumping over his head the Bible that he always carried in his backpack. They don't call them Bible Thumpers for nothing.
He railed that God condemned homosexuals, and so therefore the US should never allow homos any civil rights at all. None of the students knew that *I* myself was a gay man. Nor did this particular young ranter know that his own aunt was a lesbian who worked at a gay bar I attended 20 miles away! Or that his grandmother, whom I assumed was straight, was also a regular patron there! He was ignorant in more ways than one.
I would love to have demolished his statements myself, but that might have been unprofessional, and perhaps less effective than peer pressure.
So I invited his fellow students to comment on his statements. They tore him apart. To the point where I had to intervene, and defend HIM, and his right to free speech. Just amazing, and in a conservative rural area.
But even 10 years ago the attitudes of young people regarding gay rights were evolving. And we see it today in polling, where that generation is now in full influential adulthood. I witnessed it as a microcosm of what is happening throughout the US today.