i asked the trainer about that class when i signed up for the puppy obedience class. she said it's more of a class for humans than for the puppies, like a potty training seminar. reviewing the do's and don'ts of potty training as well as techniques. we reviewed some of that in puppy training, but not to the level of detail as the potty training class.
one of the thing i learned from puppy training at petsmart, which i've never read from a website or book (or maybe i'm just reading the wrong stuff...) is that i should use a different command for pee and poo. the trainer said "go potty" for both is too generic. with puppies it's best for the command-behaviro relation to be as specific as possible. so now i'm using "go potty" for pee and "go poo-poo" for poo.
i'm sure they'll go over techniques like that in class. and of course, some people, like me, learn best, when it's demonstrated to me, rather than for me to just read it. it sticks in my head better.
and for $15, it's not that bad.