Good solution, but there’s an ACLU type waiting to sue you for infringing on the student’s right to listen to anything they want whenever they want.
The ACLU loses most of the lawsuits they file, that would simply be yet another one. Interestingly enough, not only is there no right to privacy for data on electronic devices brought onto school campuses, there is even specific indemnity for educators in case that data is compromised or lost, even through direct malicious action, in California.
That being said, the law means nothing to the ACLU, and you're right, they'd probably file a lawsuit, then file a lawsuit because not enough money is being spent on kids.