It might be a good idea to stand back a bit and look at what your
objectives are for the class. If the kids are meeting the objective or
getting their work done, the surface noise might be something you can work
toward accepting. I often find myself at wits end because it is so noisey
in a class. It makes me feel chaotic and frazzled, but the noise doesn't
seem to bother the kids. (I wonder sometimes if they are getting noisier
because I am raising my voice to tell them to be quiet all the time.) It
might be unrealistic to expect 25 - 30 adolescent kids to sit together in a
room and not make any noise. Its what I need to make art, but probably
they can function in it just fine. Don't torture yourself.
Just a thought.