@contrex,
I had three friends who went out with teachers when we were in highschool. My friend Robin was 17 or 18 and this young English teacher she was going out with was about 24 or 25. Another friend I had named Lisa was going out with a psychology teacher- he looked older than mid-twenties- but I don't know how old he was for sure.
And my friend Laurie was going out with the Driver's Ed Teacher.
We all knew about it - nobody tried to keep it secret or anything. If I remember correctly Robin's parents even knew about her and the English teacher. She got accepted to the University of Pennsylvania and Rice in Houston, Texas and they told her they'd only pay for her to go to Rice, so she'd have to move far away from New Jersey so she couldn't continue to see this guy as easily, so they weren't too happy about it - but they didn't forbid her to see him or anything - and no one got fired.
I don't know, it didn't seem to be such a big deal back then. My first boyfriend was 7 years older than me. My parents didn't let me go out alone with him until I was eighteen and then after that - they expressed that they would have been really, really happy if I'd married him - they thought he was a great guy with a good future.
I mean, I don't think the significant others should be in the classes with the teacher - if they're going out with them, they should be put in a different section with a different teacher, but I wouldn't really have a problem with my 17 or 18 year old daughter going out with a 23 or 24 year old guy - and if he was a teacher, but not to her - so what? I'd even think that might be good.
I have a friend who is about ten years older than his wife and she was his student one of the first years he taught. They didn't go out when he was teaching her, but they both said the spark was always there.
My son went out with a 25 year old girl when he was 18 - they worked together. Some people are just more mature than their peers and are drawn to older people. I don't see a problem with it.