Others have already pointed out my thoughts on the issue, but I'll say it again anyway so the op knows there is another out there in the "likes a charity gift" column
My mind is never far away from teaching. I'm always mentally taking notes of cool things for the classroom, or finding resources and squirrelling them away. So, if a student bought me a gift of a donation to a charity that supports anything within the educational realm, be that for books or uniforms, breakfast clubs or laptops, Australia or Cambodia or Timbuktu, I would be delighted and touched.
Great gift idea imo, op.