I’m hoping that students and newer teachers alike might get something out of reading this post.
The title of it is a play on an old expression that I don’t like much; “those who can’t do, teach”. The original expression assumes, of course, that teaching is some sort of lesser ability which is what people resort to when they can’t be “stars” at the real thing. The fact is that teaching is not something anyone can do! It is often thought that because a person knows how to do something really well, they can naturally also teach it. Teaching, however, is a completely different ability and/or discipline. Why do you think people have to go to school to learn how to be teachers? 
So if your brother is a great guitar player, it doesn’t mean he can teach you. In fact, he might have the opposite effect of discouraging you without meaning to!
Students have often come to me having been to another teacher before, and most of the time, the change of teachers is for a innocent enough reason such as the original teacher or the student moving away. But occasionally I come across students who have tried another teacher who may not have been so good at the “teaching” part, which is everything! I’ve had complaints that a teacher would sit there and noodle on the guitar rather than pay attention to what the student was trying to learn, or that they just didn’t know how to, or take the time to explain something very well. And just because a teacher is teaching through a music store, that doesn’t mean that they’re good either!
Knowing and teaching are two very different things. Knowing something is one element, and teaching is being able to find a path of communication that enables the teacher to impart that knowledge. Most of the work for a teacher is finding that path, because all students are not created equal. Some are auditory learners, others are visual, and most a combination of both. A good teacher will spend time figuring out how to communicate something to the student, rather than simply have a set agenda as to how quickly or how much a student should learn.
I repeat myself a lot, something that drives my daughters nuts! But this is because I’m always looking for a better way to express or explain something. I find that my annoying habit of repetition is something that really benefits a guitar student. For beginner students it is especially difficult to hear everything that I’m explaining at first. They are very focused on getting their fingers in the right position, being able to make some kind of sound on their guitar, or trying to remember the names of things. But over time as I explain the same bits of information again, they begin to hear me and start applying what they are hearing.
A good teacher can take one look at a student and know when they’re not “getting it”, but often it’s a matter of fully listening to a student’s questions, and giving them the time and space to ask. You can never assume anything, especially that they’ve grasped what you’re teaching them, until they can repeat it back to you, perfectly or not, without your help.
Time is also a important factor when it comes to a teacher’s experience, because we never stop learning either! The longer someone has taught, the more they have learned what works for most students (I say ‘most’ because there’s nothing that works for every student!), and can identify what’s happening if a student is not getting it. There is no better teacher than experience. Having said that, I realize that there are a lot of young teachers out there who are probably more tuned into certain songs or techniques than I am, so youth can also be a positive.
So this is also very important for budding teachers to note: KNOW when to take on a student and when not to! If the student wants to learn Bach and you want to teach him shredding, that’s a student/teacher combination that isn’t going to work. Unless you’re classically trained, don’t do it and don’t pretend to. Equally as important is how you and a student feel about each other. Meet first and get a sense of what they want to learn, while they will get a sense of what and how you teach. If it doesn’t feel like a good fit, it’s okay to say no and suggest alternative teachers in your area.
One last and extremely important note to teachers: people can be very sensitive about their musical abilities. I have had students who’ve come to me as adults, having been totally devastated as kids because they were told they “can’t” sing or play. This can completely ruin their future experience of music. I want to throttle people who call themselves teachers and say horrible things like that to their students. Everyone can sing and everyone can play. Remember that.
Unfortunately, our culture doesn’t help much either, giving so much attention to the “stars” and making us think that unless we can sing and play like that, we shouldn’t bother. Your job, more than anything else, is to nurture and encourage your students to do the best they can, but more importantly to ENJOY it!
Good luck out there!
IJ
Well said! I’ve been teaching for about ten years now, and I can relate to all of your points!
I’ve had a few shredder students along the way..I myself can play pretty fast, but not enough to replicate every solo brought to me. However I use those lessons to implement knowledge of the scales being used, key and time signatures. We get out the metronime (or drum track) and start in a logical fashion. Loved your thoughts on the subject overall. A godd teacher should, as you mentioned, inspire and encourage, with experience to back it, and not simply strut his/her own abillities in the learning environment.