I think it's really important to get our students listening to more music. Sometimes I get really into it and assign awesome, hard-core listening assignments (like listening to a whole bunch of pieces by a specific composer, and writing down things you like about each piece, and such). But sometimes I think it's important to just throw in a quick, simple listening assignment that goes along with whatever the student is working on.
Simple listening assignments are great ways to teach about music history, famous performers, the musical periods, or about musicality and interpretation.
Have a beginning student playing the super simplified "Ode to Joy"? Have them listen to the REAL deal and see how joyful it sounds!
If a student is learning a classical piece, have them listen to some good recordings of the piece and get some interpretation inspiration!
One of my students played a simple piece in her method book that sounded a bit impressionistic - in fact, it was almost exactly like the first line of Debussy's Reverie. We talked a little about impressionism in music, and I played a line or two of the piece for her, and then assigned her to go home and listen to the whole piece.
I recently had a student playing in her Faber & Faber "Popular Repertoire" book the song "What a Wonderful World." Well, she had never heard the song before, and didn't know who Louis Armstrong was! So I assigned her to go home and look the song up on YouTube and take a listen.
Listening assignments can be simple and spur-of-the-moment, but they will really help our students become better musicians (and maybe enjoy playing their pieces a little bit more!)