3 Hand Position

Hand’s natural position at rest
Bring this natural hand shape up to the keys. Did you maintain the same shape?

Hand position on keys
Collapsing Knuckles
Many beginning pianists find that their first knuckle (the one directly above the fingernail) bends backwards as they play the key, especially on the ring and index fingers. This joint can be strengthened and trained to remain firm. The first step is simply to notice how it bends and mindfully straighten it. You can also make O shapes with your thumb and other fingers, as pictured below. Press firmly to strengthen the knuckle in a rounded shape.
Another valuable exercise to strengthen the knuckles is a “finger pull-up.” Close the piano/keyboard lid and lay fingers 2-3-4-5 flat (the thumb can rest gently off the lid). Slowly and firmly raise the palm. Watch your knuckles closely and ensure that they bend outward rather than collapse inward.