Look, here is my friend Nick (below in the green shirt). He teaches at a school in Castro Valley. He chaperoned high school kids on a choir ensemble workshop in Seattle.
I dragged Mia to watch the kids sing and then we did a mini tour of the University of Washington.
Here are Nick's kids being coached by a fabulous person. I don't know who he is, but he would listen to the choir, suggest things, and then they would improve leaps and bounds. I wish I had his knowledge of music.