Maintain an appropriate fun-to-work ratio.
This ratio will change depending on what's going on in any given student's life. Are they in the middle of finals? Increase the fun. Are they on vacation and up for a challenge? Increase the work.
In my struggle to be a thorough teacher, I sometimes forget to let students stop struggling and enjoy doing that which they do best. This varies greatly from student to student. Here are two examples in ways which I've succeeded and made mistakes in the past month:
Leo, a brilliantly talented boy with loads of natural facility and an instantaneous photographic memory, needed a "big" piece to challenge him. I gave him the Clementi D Major Sonatina, Opus 36, No. 6. I didn't think it through carefully enough. Coordinating hands while playing scales isn't his strong suit. Since I knew he needed to work on that, I thought this piece would be a good opportunity to work on that. And it would have been, except that the work to fun ratio was off. A shorter piece with the same challenge would have been a better choice. It was too disheartening. He learned it. He tried to be a good sport. But the polishing and getting it up to performance level was getting him down. We dropped it. I had forgotten that my ease in scale playing sometimes makes me think scales and sonatina playing will be equally fun for a talented student. I made a mistake.
Yesterday I got it right. Elena started with me eight months ago as a beginner. She's had several years of violin study, so her reading skill in treble clef far outweighs her bass clef reading. We're working on that. But yesterday, I thought, "What if I give her something to reward her for all her hard work that doesn't include anything that's challenging for her? No LH reading that she will have trouble with, and lots of fun." Voila - Vanishing Villain. No eighth notes, simple arpeggio repetition up and down the keys, and even a big exciting glissando to end it all. She'd never used the pedal before, so I taught her that as well on this piece, knowing that she would catch on in a flash. Because so many things come easily to her, I often try to work on the things that don't. But that's not always the best idea. I like to do things I do well. I bet you do, too. She was in heaven.
There are other ways to mix up the work to fun-to-ratio. What are your favorites?