Recital participation to be a dropdown with more options than "yes"/"no"

It's difficult to tell if the Recital Box is checked or unchecked purposely, or if it's just on the default from when a new student enrolled. Would like to have a dropdown of 3 options: "unknown" (which would be the default setting,) "yes", and "no". This would eliminate all the double checking and searching for whether or not a student has signed up, opted out, or done nothing.