Yup, corrections aren't going to help you. They will make it worse. Especially if you have a very drivey dog, which could be the case since the dog looks pretty BC. Punishments only suppress behaviors...Suppressing drive won't work. The dog WILL become frustrated and the drive may show through other even less desirable behaviors.
It sounds like the environment was just too charged and he got overstimulated. If that's the way it's going to be, you're not going to benefit from it. Also, please don't be afraid to tell the trainer NO when she wants to do that to your dog. You know whats best for Theo...You know that corrections are no good. Stick to your guns and stand up for him.
The goal of puppy classes isn't really to get the puppies to perform, so I'm sorry you left feeling so poorly and that it didn't turn out to be a good experience
. The point is mostly to get them socialized. A lot of higher strung puppies aren't going to be able to focus enough to do commands. That's normal, he's just being a puppy.
I personally never took puppy classes because I can socialize my dog on my own. We work on commands in my room first, then move to the living room, then outside in the backyard, then front yard, then other places like petsmart. By the time he was 5 months old, he was performing tricks in front of a class of 30 children.
Anyway, I know you payed for the class, and you should keep going. But just remember that you're the one in control. You don't have to do anything they're doing. If you need to get up and remove Theo, you can. If you need to stay further away at a distance where Theo does better, you can.
One last thing, will Theo tug? If he tugs, I can help you channel his drive.