Ach, how can there STILL be such a stigma about browsing porn? The internet has been around for long enough that it would surprise me more if someone DIDN'T browse porn, and if anything, it's the "informant" that should be taking the shit for snooping around in private matters. It's not like you can tell people apart by what their particular taste/orientation is before it actually becomes relevant, and it most certainly does not have anything to do with work efficiency. I hope your teacher doesn't get any more fallout from that. :<
If someone went on the teacher's home computer and shared that browser history, I'd be 100% agreed. I think the issue here is less that the teacher watches porn and more that he could potentially be watching it at school. Hell, maybe the iPod's history showed that he did, I don't know.