(Don't know why this didn't post in March. Wrote it March 1!. So, a bit delayed, and the Sonatina Festival was canceled, but the rest of the post holds true.)
My kids are preparing for the Sonatina Festival at the end of the month. They need to play, from memory, one movement of a sonatina, as well as one other contrasting piece, also from memory. We've been working on this music since January, and most of my students are ready and eager to perform.
In addition to notes, rhythm, rests, dynamics, the how-to-play-the-music details of performance, I need to teach and reinforce the how-to-play-through-mistakes details of performance. That is the hardest part! I think it's human nature to want to fix our mistakes before moving on. In music, we can't take the time to do that. The music continues, and we have to keep up!
So how do we go about playing through mistakes, picking up and moving on? Of course, knowing the music, inside and out, backward and forward, goes a long way in covering mistakes. I suggest playing from memory, occasionally, but also consulting the printed page during practice sessions. Visual reminders during practice will aid the recall during performance.
Slow practice is also helpful. We often want to speed through the difficult passages, but that allows for holes in our learning, for sloppy execution of phrases, and for memory slips. Yes, you need to play at tempo occasionally during practice, but it pays to slow it down, use a metronome, play every note, and of course, review those tricky sections over and over.
Another trick is not always starting at the beginning. When practicing, jump around, play the last line first, play up the page instead of down the page. I had a teacher once add practice numbers, and during the recital he would call out a number and I had to skip to that section. Needless to say, I knew that piece very well.
On that rare occasion when you just don't remember the next note, skip it, jump to the next section. No one else has the score, no one else knows the music like you do. Fudge it, fake it 'til you make it, but don't let on. Maintain your poker face. Shrug it off on the inside, but don't actually shrug! And whatever happens, take time to bow, to show your appreciation to your audience for hearing you out, and walk off the stage with dignity.