As I posted in another thread:
New "Digital Video Techniques" magazine issue (9) has a group test of budget camcorders. They review the Canon MV890, Panny NV-GS27, JVC GR-D340, and Sony DCR-HC24.
Marks out of 10:
MV890 7
NV-GS27 8
GR-D340 8
DCR-HC24 7
(Note the MV960 is similar to the 890... the 960 has DV-in, the 890 doesn't).
The JVC doesn't have slow motion and frame by frame direct from the camera. The Panasonic GS27 doesn't either, but the GS37 (like the 27 with more features) does. The Sony HC24 also does. I don't know about the Canon (they don't post their manuals on-line so it is hard to find these details).
The Panasonic GS37 is available for around £240
http://www.pricerunner.co.uk/sound-a.../prices?q=gs37
Sony HC24 is just over £200
http://www.pricerunner.co.uk/sound-a.../549440/prices
Or go to £220 ish for the Sony HC35 - like the 24 but has DV-in and a docking station (so you could leave the docking station attached to a PC)
http://www.pricerunner.co.uk/sound-a.../549412/prices
When you say "played back via PC onto a screen for the kids to review", and doing slow-mo from the camera, this would mean using the PC has a display (so the PC would need video input). I assume you probably have a projector which you typically connect a PC to, to show things to the class on a big screen? If so, the easiest would be to connect the camcorder directly to this projector, and not use a PC at all.
If you want to edit the footage on a PC then of course you'd want to connect it to the PC via firewire.
Mark