This time,
③ Be able to freely use the black and white keys
I would like to write about this.
Most people who have only just started playing the piano for a few years find it easy to make mistakes on the black keys, or that it is difficult to play the keys at the back of the keyboard. For this reason, we often see children who move their hands to the back only when they are playing the black keys, and then as soon as they finish playing the note, they immediately bring their hands back to the front. However, this is a wasteful movement, and it can be a major obstacle when playing difficult songs.
Hanon is also very useful for solving problems like this. Hanon numbers 1 to 31 are all written in C major, but you can practice transposing them into various keys.
If you transpose to a key with three or four or more sharps or flats (such as E major or D flat major), you will practice playing more black keys. This will also prevent you from moving your hand back when playing white keys, so you will naturally train yourself to play the keys further back on the keyboard. By continuing to practice in this way, before you know it, you will be able to play both black and white keys, as well as the keys further back on the keyboard, freely and without any resistance.