Anatomy and the Sound Point (1.2)

Allow any finger that is not playing to remain at rest, or to come to rest as soon as possible, on the top surface of the keys.
Keep the thumb loose, in comfortable alignment with the hand - not twisted or cramped.

Make a tight fist. Let one finger out and try to move it (by bending it) really quickly.
Now contrast this by letting all the fingers out and moving freely from the knuckles. You can move all fingers together, simultaneously, or in a "wave" pattern.
We have opposing muscles in our forearm called flexors and extensors. Opposing muscles are used optimally in alternation in piano-playing, not simultaneously.
Playing from the knuckles is the freest way that we can use fingers. It is one of the motions for speed in the body (in piano playing). The other is rotation.
If we try to play with fingers that are curled up to be all in a "straight line" we are engaging opposing muscles simultaneously. When we pay attention to this, we can feel how difficult it is.
Instead, since our fingers already are of different lengths, we can play in three planes of motion. It is much easier and freer to play this way!
Observe your forearm to see and sense opposing muscles.
Move your fingers up and down from the knuckles.
The flexor muscles draw your fingers toward a fist.
The extensor muscles allow them to extend outward.
These flexors and extensors are antagonistic. If they contract simultaneously, stability is increased, but at the expense of flexibility and speed.
Therefore, this antagonistic relationship must be respected.
Learning to use opposing muscles in alternation results in maximum freedom at the piano.

On an acoustic piano, the point of sound takes place at the escapement, where you can perceive a bit of friction, or a bump.
We travel through the sound point in three main ways:
1. surfacy (too shallow)
2. keybedded (playing to the bottom of the keys or aiming beyond the key bed, with no rebound)
3. "cushioned" (decelerating just past the sound point and rebounding off of the key bed.
For a shallow sound, aim for the top of the key surface. Notice that the sound is superficial.
For a keybedded sound, aim well below the bottom of the key bed, and notice the harsh sound that results.
For a cushioned* sound, press a key down and hold it from the edge with your left thumb. With your right hand's second finger, practise dropping onto the depressed key. Then, let go of the key with your left thumb and drop into the key with your right hand's second finger, and allow the tone to sound. Rebound off of the key bed, just after passing through the point of sound.
The "cushioned" sound is the one we use most of the time when we play the piano—and is the "default" sound in Entrada. The "shallow" and 'keybedded' sounds may be utilised when special colours, effects or voicing are desired.