But I can do it in the practice room
Every week I hear students play badly, then tell me, “but I can do it in the practice room…”
Here are some reasons things might go more poorly in a lesson than in a practice session, and some strategies for dealing with those problems.
- It’s possible that you’re not really playing any differently. Things seem worse because having someone else listen heightens your sense of what you really sound like. Try recording yourself while practicing, then listening back. It can be a painful revelation, but it can bring problems to your attention and improve your ability to really hear yourself as you play.
- It’s possible that your mastery of the music is really only borderline, and the normal stress of having an audience is enough to cause trouble. This is what I call “sight-reading mode.” It’s not that you are necessarily playing the music for the first time, but you are still at the point of having to mentally process each note as it goes by. For more stress-proof performance, put in more slow, accurate repetitions when practicing to build your muscle “memory” and aural memory.
- It’s possible that your mastery of the music is good, but your stress is above normal. In this case the problem isn’t your practicing per se. Improve your ability to play in front of others with techniques for managing performance anxiety. These might include healthy lifestyle habits (sleep, nutrition, and exercise) or mental exercises (like visualization, affirmations, or mindfulness practice).
Don’t make excuses, look for solutions!
It seems like there’s very little I do these days without a computer. Here are some ways I have used a laptop to boost my practice sessions. 
During the past few months, I’ve had the opportunity to do some traveling with my instruments, on a number of airlines and through quite a few airports. Here are a few thoughts on getting instruments safely and smoothly to your destination.