Benedict, my 11 month old male GSD is very vocal. He barks, sighs, whines, etc.
If I go in the bathroom and shut the door he lets out a big sigh and sits in
front

He barks mostly when excited. If he was driver he would be one of those who honk
in traffic jams even though it does no good
We began a 5 week class this week to prepare for the CGC . As soon as we pulled
in the parking lot he recognized it as the place we go for training even though we had not been since November and began barking excitedly in the car. I waited
until he was calm before letting him out, and walked him around the parking lot
for awhile.

He did very well with the three other dogs in the class, let them pass in all new to him, let them pass in fairly close proximity, He easily did all the behaviors asked for.

The problem was during the times when he had nothing to do, while the trainer was talking to us he would bark constantly. The second trainer put a barrier in
front of him and it did not help. She then took started working basic commands with him and as soon as he had something to do he was fine.

Any suggestions on how to teach him to not bark? It is not an aggressive barkat all. Just an excited, "lets get this show on the road bark"

One the owners of the quieter dogs gave me the look I used to get when my kidswere bad in church I am thinking next week to bring a frozen stuffed kong to occupy him during the times the trainer is talking

Does he know "Quiet!"?

I taught my dog the command for quiet by first teaching her "Speak!". Once that was solid I would get her barking excitedly and then switch to the new command, mark and reward the silence. It was really easy and has been very effective.

It went something like this "Speak! Speak! Speak!...Quiet!".

At the new command she would pause in confusion and I would mark it.

Once they know it the trick is to give hem the command before they start barking. For example if I hear her growl while she is laying in the hallway, I know a dog is about to pass by the house. I tell her "Quiet!" before she gets to the window.

When I do this she will stand at the window and give muffled, closed mouth huffs. Its much nicer to live with than the crazy loud guard dog barks. I have also used it in public with success.

Its pretty cool, very convenient, and your neighbors will think you have the best dog in the neighborhood.

You said that he was quiet when he had something to do, so when the trainer is talking, do not disconnect from him, give him something to do.

So when I am working my dog in a group setting and someone stops to talk, I ask my dog to sit in a heel and focus. I drop my head and look at him, while listening to the trainer. This way he is quiet and he is working. I can also practice having him focus on me even when I am not looking at him.

So if he already doesn't know "focus", just use the marker training to teach him to look at your face/eyes and reward. Then start with small distractions and work your way up.

It really just sounds like he doesn't just want to sit there, he wants to work. So give him something constructive to do and he will be too focused to bark.