"¿Y tu?" doesn't work well, since you are using 'tu', referring to you.
If you would like to ask for the class instead of the person, you would say "¿y la tuya?". I'm afraid that there is not anyway to shorten any more than saying this if the context has been establish already.
By the way, it is not 'tu', but 'tú' (with an accent).
Example: 'tu casa, tu ...