Conrad Honicker, 17, who has been active in Tennessee's LGBT organizations, was also surprised at similar blocks at Knoxville's West High School.
He, too, had trouble researching an English paper -- "Adverse Effects of Heterosexism in Society.'
"I couldn't find any research on the pros and cons," he told ABCNews.com. "
"It doesn't make sense because Knoxville County has a good anti-bullying policy," said Honicker, who wants to pursue gender studies and psychology in college and hopes to be a guidance counselor.
"My point is that students and teachers don't have access to these resources for anti-gay bullying, which is inconsistent with school policy that addresses the underlying homophobia in Tennessee schools."
His school's librarian, who also sponsors the gay-straight alliance, has sent her own letter of support to the ACLU.
"As librarians, we champion intellectual freedom across the board," said Karyn Storts-Brinks.
As for Emitt, who will attend community college in the fall to study education, he said Central High School has been generally supportive of its LGBT students, despite the block.
"I was shocked when I couldn't get on those Web sites," he said. "It was frustrating. I didn't really think it could be legal. I thought, 'Is this allowed?'"
The Tennessee School Librarians Association (TSLA) says it's not.
"If a student is not getting equal access, then it is censorship to some degree and it's not right," said TSLA President Bruce Hester, who is sending the ACLU a letter of support.
"As long as it's not pornography in nature and it's nothing elicit for students under 18, then I can think of no reasonable reason to deny access, by whatever name it goes by."