No power? No problem. 1) Create your own instrument. You can draw it, sculp it, or even build it out of found objects around the house. Explain what family of instruments it would be in and why it belongs there.
2) Write a song. You can use instruments to compose the song or just write the words (lyrics) before trying to come up with any additional layers.
3) Make flash cards for the treble or bass clef notes (depending on what your class is working on. If you aren't 'sure...do Treble Clef.