Why do people tend to squeeze the keys?
The piano key is not a button, it is a lever.
When it is lowered on one side it rises on the other, it is not a button that must be pressed to the bottom to be activated.
The reason why people tend to press is the fact that sound travels very slowly, at 340 meters per second.
When a key is lowered, the hammer hits the string, the string starts to vibrate, putting into vibration the soundboard.
Finally the sound arrives, more or less when the pianist reaches the bottom of the key.
This is what deceives inducing to squeeze.
The pianist deceives himself thinking that squeezing produces sound.
This is one of the many reasons why it is essential to start playing "staccato" instead of "legato".
The ﬁrst step therefore is to start with a "staccato with sliding touch", which consists in pressing the key from the point closest to the fulcrum and then retracting the arm backwards, until losing contact. In this way the ﬁnger runs over the entire visible portion of the lever.
Subsequently the hand is made to stop near the tip of the key, without detaching and without pressing. The sound becomes the "tenuto": not yet the legato, which obviously needs at least two notes. It is important that the arm is slid with the ﬁngers in a rounded, not arched position. It is good to start with the second ﬁnger, which is aligned with the arm, then with the third and later with the fourth.
Pulling the arm has the function of getting used to work with the shoulder, with the trapezium and with the deltoid.
When these movements are assimilated, the "staccato with forearm touch" can be taught: the upper arm remains still while the forearm lifts pivoting on the elbow. The pressing of the key should be done as if the ﬁnger served to take a little cream from a cake.
Traditionally, instead, the hand is set to the ﬁve notes position in a stiff position: one ﬁnger at a time is lifted making the extensor muscles work above all.
Starting with the articulation of the ﬁngers is profoundly wrong: moving ﬁngers through the extensor muscles is a point of arrival, not a starting point.
The technical education should not start from the ﬁngers, but from the arm, as Chopin himself said (even if he did not teach it).
Chopin was recommended not to play only with ﬁngers, and not with the wrist alone (as Kalkbrenner wanted) but also to use the forearm and the full arm.
This was the romantic technique, which unfortunately did not give rise to a new teaching method because the teaching system remained what it was before: ﬁrst of all, hammering and then hammering and then hammering...