[1.II.20] Weak Left Hand; Using One Hand to Teach the Other
Students who do not practice HS will always have a stronger RH than LH. This happens because the RH passages are generally more difficult, technically. The LH tends to get passages that require more strength, but it often lags behind in speed and technique. Thus "weaker" here means technically weaker, not strength-wise. The HS method will balance the hands because you will automatically give the weaker hand more work. For passages that one hand can play better than the other, the better hand is often your best teacher. To let one hand teach the other, select a short segment and play it rapidly with the better hand, then repeat immediately with the weaker hand, one octave apart to prevent collisions. You will discover that the weaker hand can often "catch on" or "get the idea" of how the better hand is doing it. The fingering should be similar but does not need to be identical. Once the weaker hand "gets the idea", gradually wean it off by playing the weaker hand twice and the stronger hand once, then three against one, etc.
This ability of one hand to teach the other is more important than most people realize. The above example of solving one specific technical difficulty is just one example -- more importantly, this concept applies to practically every practice session. The basic reason for this broad applicability is that one hand always plays something better than the other, such as relaxation, speed, quiet hands, and the innumerable finger/hand motions (Thumb Over, Flat Finger, etc., see following sections) -- anything new that you are trying to learn. Therefore, once you learn this principle of using one hand to teach the other, you will be using it all the time.