I have one rule about my passport--I NEVER give it up. If a school needs to hold it for some reason, I'll give him a copy of my picture page, but that's it. If a copy wouldn't be good enough, I'd find another school.

I've heard of white-faced idiots in Thailand who've given up their passports when going to work at schools, only to have those entrusted with those passports walk off and leave them on copy machines at places like immigration.

A farang passport in Thailand is like a cell phone here. If you put it down and turn your head for five seconds, it's gone. If you leave your cell phone/passport someplace, it's history, you can count on it.

Never entrust one of these absent-minded Thais to your passport!