Just my humble opinion.... and
what I tell the kids w in the past when I have done this.... "This is part of your homework and should be treated as such. You can fail band for not doing your homework the same way you can fail your other classes". If they have time for the rest of their homework then they have time for all of it. Besides... practicing is more fun than math. It only takes a few zeros in the gradebook for them to figure it out. And, if they don't, then that tells you there that they are not cut out to be band kids.