Makes for a pretty volatile mixture in general.
When I was in high school, all female teachers were UUUUGGGLLLLYYYY and such a concept was beyond the realm of possibility.
Consider how the typical 17 year old guy might react to a beautiful woman offering him sex. She would be the center of his world. Having sex with her would be the only thing he would think of, by day and in his dreams.
There is no shortage of women who would find the prospect appealing.