Fun with Yo Yos

I'm not talking about plastic balls on a string, but rather students who are up about piano lessons one minute, down the other.  I have one particular student who hits the extremes on both ends.  He either finds piano a waste of his time, or he truly adores it and has fun exploring new things and playing his favorites.  While I can't make everything about piano lessons "fun," I hope to stay flexible enough to make it worth it to him.  It is work sight reading a new song, practicing a tough measure over and over, stretching the hand into new positions.  I'm learning how to keep a balance of enjoyment and beneficial challenge to keep him growing. But hopefully we can get through to the reward at the end  - being able to play music that's beautiful.