My daughter twirls the baton for her college band. Can I deduct the cost of her costumes, batons, shoes, and tights as "materials" for college?
I don't have a definitive answer. It might depend on what educational benefit you're trying to obtain. There are different expenses for different credits/deductions.
I think one thing needs to be kept in mind...is this course required for her course of study?
Here is a link for some guidance in this area. Look at the different expenses allowed for each type of credit/deduction.
Unless you can tie this to a requirement for her course of study, you can't treat as eligible education expenses. Participation in band sounds like an extracurricular activity to me.