While ukulele is not a “bluegrass instrument” it can play along at a bluegrass jam and “do no harm” as long as they hit the right chords and stay in rhythm. It’s likely they won’t be heard very well, and will not be asked to solo unless they can play melodies. They can still benefit from the class… learning bluegrass repertoire and etiquette, meeting new people, and being exposed to real bluegrass as played on the typical instruments. We’re always glad if a uke player decides after the class/camp to obtain a mandolin or guitar, whose similarities to ukulele work as a good head start. In any case, we do welcome ukuleles and hope you decide to join in!