Help!

As some of you know, I've been teaching piano for a few weeks. But I have a small problem- 30 minutes of piano just isn't interesting for children of 6 years. Which half of my students are. I need to make things interesting for them, but I really can't think of any games that would be benificial. Does anyone have ideas?
On a different topic, our first marching band competition is a week and a half away. AHHH! The Front Ensemble (or is it Center now?) rehersal was very frustrating last night. Our parts are harder than before (4 mallets, baby), and we're having a hard time listening in. If this keeps up, we're toast!
Anyways, if anyone has ideas for fun musical games, please tell me!