As with any other subject, it is almost always a good idea to involve the greater school and outside community in educational experiences. Community artists or performers provide great support to the teacher's efforts to show that the arts are indeed relevant in the real world. Public art shows and performances also show scholars that their efforts are accepted and valued by the world out there, building confidence like nothing else can.
However, another way that I think the arts should effectively connect with the greater community is through service. It is easy to believe that the arts is about showing off for others so that they will admire you. We see many models of that in our society today, though we have a natural distaste for it. Instead, it is important for scholars to learn that creating and sharing art is an act of altruistic service. It is, quite literally, learning how to find yourself and then sharing it with others.
I like to use a simple formula with my classes "Surface - Inside - Out". I mentor the scholars in discovering all there is on the "surface" of a piece of music: all the right notes and rhythms, tempo and dynamic markings, words and composer-indicated expressions. We work to get it all right. But we don't stop there. Next, we delve into the meaning expressed in the words, melody, harmony, rhythm, texture, etc. of the piece and try to feel the deeper truth and beauty within the piece. We seek it out with our minds, but we also feel it out with our hearts. In short, each person determines what the piece means to them, how it personally connects to their own thoughts, feelings, and experiences. Finally, I invite the scholars to share part of that personal meaning with each other, and with the audience through their performance in the concert. They don't need to share everything; many things are too private to share publicly. But they can share many authentic and meaningful personal truths through their facial expressions, emoted feelings, and vocal inflections as they perform the piece.
In sharing these personal meanings through performance, the scholars effectively connect their technical skills with the authentic Truth-Beauty-Goodness they have discovered in the piece and share it with their audiences. They give their audience a gift of genuine Beauty, a priceless treasure in this world! And what is more, they feel that Beauty even more strongly from the giving of it. This is a genuinely transformational experience, for both the scholar and the audience. This is the greatest gift the arts has to offer, and it is possible from even a moderately-skilled and -experienced scholar in a school.