I used one of these: http://esupport.sony.com/US/perl/model-home.pl?mdl=ICDP110 to record therapy sessions for use in grad school presentations (I got written permission from my clients). It comes with software that allows you to download it to a PC (USB 2.0) in HQ .wav format or mp3, mono mp3, etc. I burned mine to a CD and presented in the TV/DVD-CD Player combo in the classroom. It sounded great!!! Best when I used the low sensitivity setting (Less background noise). Everyone else used portable cassette recorder/players that sounded pretty bad!!!! I looked like such a pro!!! =]
As far as playback on the unit itself, it would not work too well in a classroom setting as it would not be loud enough. It does have analog output (1/8 inch), so it could be plugged directly into something else for amplification.
I used disposable lithium AAA batteries and did not have to change them often.
Brad
Atlanta