Grammar Police People

[Jeremy]

Nick: I think between us we've just lost a small continent, who may not get that gag :-)

Morgan: Buy it. It's an entertaining read and, on occasion, a handy reference.

(IMO, a colon & semi-colon combo wouldn't have changed the sense of what you were saying, unless you wanted a bit more emphasis).

Selena: possessives in this case, as it's plural. Some people would grind their teeth at using an adjective as a noun, but hey-ho.

It should definitely be classes' from where we all seem to sit, if there's more than one class.