Drop-down Form and Check Box Combined—Bad Practice?

I am working on a form wireframe, and getting stuck on this one part.

The user can either pick out an extracurricular involved, or choose "none", if not relevant. Having both a drop down and a check box seems a bit too complicated to me though. Would including "none" in the dropdown be better, and have the form automatically be set to that, unless the user changes it? Or another alternative I thought of was to have "extracurriculars" be a checkbox, that if checked, then exposes a dropdown menu? Would love to hear your thoughts.

Thanks in advance