Assuming competence can be the most detrimental thing to do when teaching music reading. By competence, I mean possessing the skills, knowledge, and abilities that enable the student to learn effectively, and not only have the technical skills and knowledge required but also the ability to apply these skills in reading music.
Music reading is not similar to language reading. It is far more complex, it involves a variety of symbols that represent pitch, rhythm, dynamics, articulations, and other musical elements.
Language, however, is typically linear and involves familiar letters and words, musical notation is a more complex system that requires the reader to interpret multiple types of symbols simultaneously.
Moreover, there is the factor of multitasking and coordination: finger coordination, eye-hand coordination, and hand-foot coordination.
In many cases competence needs to be gradually built before we begin teaching note reading, and unless we carefully assess and build these skills and missing blocks with careful training and reassessing we won't be able to guarantee results. Once you realize this seemingly simple fact, every lesson will become purposeful.
The typical first few piano lessons will include the following concepts:
Learn the names of the piano keys and be able to find them on the piano.
Learn the whole note, half note, and quarter notes.
Learn the bass and treble clefs and their meaning.
Recognize and read the notes of the middle C position or the C position,
Play simple tunes using these notes on the piano using the correct fingers, and using the correct hand and the correct rhythm.
Let's begin by breaking only the first concept down:
Learn the names of the piano keys and be able to find them on the piano.
To make learning the above concept possible, the following skills are the least that the student needs:
Being able to recognize patterns.
Understanding the white/black key pattern on the piano.
Knowing the first 7 letters in the alphabet.
Understanding that keys have different names and these names will repeat in a pattern every eighth note.
Good attention span.
Ability to follow instructions.
Communication skills.
If we try to move forward with the lessons, assuming the student learned the first concept, then move on to teach how to read the notes C, D, and E on the staff. Why C, D, and E? Because these are the first notes being taught in every piano book I've seen.
Attempting to break down all the concepts that need to be fully understood before being able to read these notes, I came up with the following list of concepts that require many different skills:
Understand the white/black key pattern.
Know how to read the letters C D and E.
Understand that different keys have different names.
Be able to find treble C, D, and E on the piano.
The concept of assigning shapes of notes to time values.
The concept of notes moving up and down the staff will change the note name although it still keeps the same shape.
The concept that going up on the staff means going to the right on the piano.
The concept that going up on the staff means going to the right on the piano.
One note on the paper means one key to be pressed.
Understanding that each note is written in a different place on the staff.
Understanding the concept of treble clef.
Knowing which hand and which to use.
If we begin teaching the students assuming they are competent and ignore checking if they understand the above concepts and have all the skills needed, we might be setting ourselves up for a big disappointment.
What we need to do instead is to treat every student as a clean slate and, break things up into smaller pieces, a lot of smaller pieces, we will very quickly find out that almost every student will eventually be able to read music.
I hope this post helps you realize why sometimes, no matter what you do, you can't make a certain student read music. It is most probably because of an important missing skill you haven't yet discovered. In many cases, these skills can be taught without any problems, you only need to dig deeper.
If you have any questions, please don't hesitate to contact me, I read and answer all my emails.