I am a teacher, well was until I got laid off this fall because of low enrollment. I still have my other job though. Any hoo, as for teaching, the flash drive is the way to go. Be sure she encrypts it with a password for access, those little buggers will want to get there hands on it. As for a PDA, I use one in my current job, but never used it in conjunction with teaching except to maybe take notes and use the calendar.
Now don’t get me wrong, PDA’s are great! I can get my email and even control the servers from it.