I've had two guitar teachers. One of them was a solid, competent musician and an incredible teacher. I learned more in the year-plus I studied with him than I've ever learned about any subject from anyone over any two year period. The other teacher was a brilliant musician, highly regarded and successful, played with some of the biggest names in the industry---but I hardly learned anything from him.
What was the difference between them? Simply put: the quality of the homework assignments. Keep in mind the most important rule of teaching: you're job isn't actually to dispense knowledge and expertise. Your job is to be a guide for the student's own path to learning how to play.
Understand: your students won't actually learn much during their lesson with you. They will do the vast bulk of their learning during their own practice time. The best thing you can do for them is to make sure they know how to spend that time in the best, most efficient way possible. With that in mind, my advice is to:
Assign Specific, Clear, and Level-Appropriate Homework
The great teacher had an ability to discern where I was as a guitarist and devise homework for the week that challenged me and pushed my limits without overwhelming me. The assignments were very specific and clear. A typical weekly assignment might be:
- Practice the mixolydian mode using these six different fingerings. Each fingering is associated with a specific dominant 7th chord voicing. Play the chord, then play the scale, then play the chord. Move one fret up and repeat. (He had about eight different exercises per scale: chord-scale-chord, three-note-groups, four-note-groups, in thirds, etc. A different exercise each week).
- Practice the dominant 7th arpeggios the same way as the scales.
- Play page 15 from your sight reading book (which he provided, at my cost).
- Play this tune from the Real Book, in the following way:
- Play the melody in 7th position.
- Play each chord in the following positions (then he would go through the entire tune and write fretboard positions for each chord). Play the chords in the Freddie Green comping style.
- Play through the changes using arpeggios. In other words, if the changes are BbM7-Gm7-Cm7-F7, play a BbM7 arpeggion, then a Gm7 arpeggio, a Cm7 arpeggio, and an F7 arpeggio.
- Learn this Joe Pass chord-melody.
- Write your own chord-melody for X tune.
Obviously, I was learning jazz, and this lesson might not be appropriate for a different student. But the point is that it was specific, clear, and appropriate for my ability at the time. When I went home, I knew exactly what to do and how to do it, and when I came back the next week, I could show him what I was able to learn and what I wasn't, and he adjusted accordingly. Each week, he laid down the tracks in the direction he felt I needed to go, and I simply followed them.
The not-so-great teacher was much more vague. He'd say things like, "Play that solo the way Miles would play it." That's not helpful. He'd give me homework like, "Go home and think about all the different ways you can play a chord," instead of, "Play this chord here, here, and here." I'd leave the lesson not knowing how I should spend my practice time, and so I wouldn't actually learn anything. Of my two teachers, he may have been the better musician, but I didn't get all that much out of our time together.
Know your students' current level and assign them homework that pushes them just enough. Make sure it's challenging so that they don't get bored, but make sure it isn't overwhelming so they don't get frustrated. This is easier said than done, but if you strike that balance just right, your students will have an amazing learning experience with you.