So it wasn’t much of a surprise when one came up with a question Ms Grady said she hadn’t heard in more than a quarter-century of teaching.

“If the president has an affair,” the student asked, “is that illegal?” The charge that President Clinton was intimate with a 21-year-old White House trainee is forcing teachers to ponder the sex life of a sitting US chief executive for the first time - right down to the personal details.

“This is an incredibly complicated one, because being high-school kids, they are going to focus on the sexual aspect, and really that’s the part that’s not important,” said Ms Grady, who teaches 14 and 15-year-olds at the highly-regarded Rindge and Latin School in Cambridge, Massachusetts.

In fact, Ms Grady’s students were quicker than many adult Americans to focus on the constitutional question: whether Mr Clinton had encouraged his alleged paramour to lie under oath about their relationship.

“The problem is, he told her to lie to Congress,” one said.

“He can’t get impeached for having an affair, but he can get impeached for perjury,” said another.

Some teachers have encouraged such discussions. Others, however, are uncomfortable about the topic. Ms Grady said a colleague who teaches younger children asked her: “What do you do when a kid asks, ‘What’s oral sex?”’

She had been at a loss what to say.

But Ron Evans, a professor of education at San Diego State University and co-editor of a book about teaching current social issues, said the debate could be worthwhile. “This would be one a lot of teachers would have fun talking about with kids. They would find it interesting and there would be some coverage of the moral and legal issues,” he said.

Tony Lawrence, who taught history to Monica Lewinsky, the White House intern involved in the scandal, said the discussion had been painful to him. “I feel very funny about it. We’re talking about President Clinton’s penis, for God’s sake,” he said. “I just want to cringe.”

Clinton’s new teachers , page 25