Do you recognize this scenario? You are playing a piece for your teacher, and you stop or make a mistake. Your teacher asks you to start from a certain place, and you struggle to remember where you are and how to start from there. Students often want to take the easy route and go all the way back to the beginning. Out of context, they can’t seem to find their way to start up at any given point, and keep going.
This is a matter of sight-reading. Naturally, it is always easier to start from a familiar place (such as the beginning) rather than making the effort to really read the notes and rhythm and start from right where you are. But in fact, this is an excellent opportunity to practice your sight-reading. We all need to improve our sight-reading skills to become better-equipped musicians, and when we practice starting from many different spots in the music, we not only improve our music reading skills, but we also have more starting points available to us during performance, when we really need them! If you always have to go back to the beginning to get through a certain spot in the music, you are wasting a lot of time, and not really working on the problem area.
Try this at home: The next time you stop and have to start over, only go back to the beginning of the measure in question, and practice that measure over and over, at least a dozen times, or until you feel like you can play it through very smoothly, and without stumbling or hesitating. Then connect it to the previous measure (yes, that means you will have to start from there, too!) and the following measure, as well, and do more repetitions. Now you will have really accomplished something. This is correct and effective practicing. Work on this practice habit until you can start from anywhere! Then you will know you’re a really good sight-reader!