My limited experience in relationships, of all kinds, is to try to talk things over with the people involved first. A three-year relationship is a significant thing, for everyone.
Questions for consideration:
- How does your child feel about the teacher, and vice-versa?
- What does your son want to learn (or you want him to learn) that he isn't learning? What isn't working, in your, and your child's opinion?
- What other resources are available (music camps, ensembles, schools, etc.) that could be supplementary? Some students have a bass teacher, an ensemble coach, a vocal teacher, a piano teacher, theory classes on the side, etc. So, there may be ways to broaden the experience while maintaining continuity with the current instructor, if the relationship works well.
- What is your child's true interest level? How much does he practice, play, and listen? Is his involvement voluntary is this something imposed on him? What musical projects/tunes/etc. does he bring to the table on his own? What types of music, currently, is he interested in? Is any perceived lack of growth possibly stemming from your son's own ambivalence, to any degree?
My experience is that really good teachers are always busy/popular and will have their students' interests at heart; if they lose one student they will find another. Many teachers feel honored/proud to "send someone on" to bigger things, if the student has already learned what the first teacher has to offer.
You are in a working relationship with this guide already; so, perhaps, use that relationship, first; check on their view. Then, they may be able to help you with a transition, if you all decide that its time for change.
So much of it is about "fit;" not competence or skill. How the student/teacher feel about each other has a lot to do with how seriously they take each other, in my experience. I would talk about it in those terms; not, "I think that you aren't a good teacher and I am considering firing you," but, "I am wondering about fit and interested to hear your thoughts." Etc., etc.
On a personal note, I was one of those lukewarm 'cello students that teachers dread, as a young kid. Memorized the music at the lesson, played it back a week later, would hardly touch it in between. I just wasn't in to it, even though I had some good teachers, a nice instrument, and decent talent.
When I got into the bass, another instrument, another time, I couldn't dive in deeply enough; in both cases, it had as much to do with my own youthful path as with my teachers' efforts and/or skill.
Finally, where are you? If you fill out your profile and give us a location, folks here may be able to provide additional teaching resources.
