I do not teach my son piano. But he is taking the summer off from his teacher and I decided to take the opportunity to teach him how to play by ear. Here is the process I am using.
Every day or two, he picks a new song to learn. They are simple songs like “My Bonnie Lies Over the Ocean” or “God is so Good.”
The first thing he does is learn to play just the melody in his right hand. In the beginning, this took 30 minutes or so to get it down perfectly, but he is much quicker now.
After he knows the melody well, he adds I, IV, V block chords to the melody to make a song. This is an experimental process that takes a few minutes as well to master. His teacher has taught him I-IV-V-I cadences in most keys so he just has to figure out which chord goes in each spot.
At this point, he can play the song and it actually sounds like a song. In fact, at this point, he is playing the song better than most music majors would be able to if I asked them to play a song without music.
I am now teaching him how to play the block chords as arpeggios or in simple patterns. Again, this is a learning process that might take 20 minutes to master for a song.
So, he is learning to play a new song without any printed music in a sort of interesting way with about an hour of work. And he is getting faster.
If we stay on this path, he will be arranging well within a few years and will have a huge headstart on where I was at his age. He will also be able to pretty much play any song he knows on the fly without written music. I am pretty excited about all of this.
Here is what this means to you. My son is not a prodigy. I think almost any child can do this exercise, so teach them this skill.
And by the way, yes, this is a skill. Someone recently informed me that playing by ear does not really take skill. I have no patience for that kind of silly statement. I want my children to play equally well by printed music and by ear. Both are critical skills to becoming a complete musician.