Hello, this is a middle grade paperback book I read in the 1980s. It had simple black and white pen-type illustrations. (I think. It’s possible there were no illustrations.)
A professor takes a select group of kids to live for the summer in a school bus near the beach. It is not magical. Everyone gets to choose their own bunk and decorate their area. They study nature like tide pools and write in notebooks.They have to write every day. The professor plays the guitar and write his own lyrics.
One of the songs goes something like this:
Yes is best, but next to that is maybe.
We’ll say can sometimes grow to yes,
but when they say I doubt it, you’re on your way to no.
I don’t think so, I don’t think so,
down, down, down,
there’s no where else to go
but frown and then say no.
They make a clam pit and have a clam bake. They go visit a mansion and everyone chooses a room and picks out clothes from the closet of that room to wear to dinner. One girl wears “paper ballet slippers” to the dinner and I have spent my entire life trying to figure out how that would work. Everyone suddenly sees her as beautiful.
There was also something about how they managed privacy and all the kids created their own outdoor “rooms” where they could be alone and undisturbed when they got over peopled.