Well, I'm having a bit of a frustrating day (kids, hubby, puppy - all acting like lunatics), so forgive me if I sound a little "cross".
This class has an instructor and at least one "assistant" per class. The assistant is someone who aspires to be a trainer and is there to gain experience. I'm a ashamed to say that I have a bit of a problem taking instructions from someone who is little more than half my age.

But that's my problem, not Phoebe's or yours!
So, I get to class today and talk to the trainer about Phoebe's "fear" issues. She didn't notice Phoebe hiding under the chairs during the last class, was surprised to hear that she did, and said we'd change groups for today's puppy play session (put Phoebe in with some less exuberant pups).
Of course, no sooner do I mention this, then Phoebe decides she's feeling a little more confident and now wants to play. "Great!", I think. Of course, Phoebe is used to playing with Mojo, who is more than twice her size and quite rough with his play (he likes to drag her around by her collar or lie on top of her and chew on her head

). So now she's barking and growling and trying to paw at these puppies, of whom only 2 are the same size as her, the rest are all way smaller.
This means a change of tactics. Yes, we still praise her for behaving nicely towards the other pups. But, now we're correcting her for growling and snapping. Grab the cheeks or scruff, get right in her face with a "Don't do that!", and then get her to sit for a treat. Does that sound about right to you?
Other than this rough play issue, she's doing really well! I'm really looking forward to trying her out with agility!!