This question came from a teacher who had been working with a particular student for a number of years. Everything had been going well up until recently when the student, now a teen, had suddenly started telling the teacher what he wanted to work on in lessons. He was bringing in music he wanted to learn, including music from his orchestra class at school which was much simpler then his playing level. Working on it felt like a waste of lesson time to the teacher, and she was frustrated that he'd also started asking her to teach him certain skills and techniques that weren't aligned with her current goals for him. To her, it felt like he was trying to reverse roles, and that felt disrespectful. Especially after so many years of him dutifully doing what she said, she was frustrated that he suddenly was no longer willing to just do what she'd planned for him lesson to lesson. She also feared that although his playing had developed steadily up until this point, he might not continue to make the methodical progress she'd planned for him now that he was distracted by all these other ideas he had for his playing.
My first thought was that this teacher's experience might be a small taste of what parents with teens seem to figure out pretty quickly: their kids are becoming adults, with their own ideas, interests, and tastes. For all we know, our teen students could be driving their families crazy with rebellion at home, so we could actually consider the fact that they still want us on their team as a huge blessing (and compliment!).
It's actually healthy for teens to start to assert themselves as individuals. After all, in just a few years they will be off to college and will need to start taking responsibility for themselves as adults. And in my experience with adult students, they have a LOT of ideas about what they want to learn! They bring in orchestra music, church music, music they come across and want to try, exercises and repertoire they see someone promoting on YouTube, music their friend or spouse wants to play with them, etc. Even with beginning adult students, our role becomes more of a coach than a teacher, meaning that we need to work with our student, rather than expect that they'll be satisfied only doing what we tell them to do. Although it's a very hard choice, sometimes it's best to even sacrifice our completely methodical approach to repertoire and skill building in order to keep their interest.
Personally, I prefer to team up with all my students, but giving a student more rein can feel strange, and even scary, to teachers who are used to being in complete control over what each lesson looks like moment to moment. With a young child, we can support a teamwork approach by simply allowing them to choose which string to play an exercise on, or to make up a new rhythm they can apply to Twinkle instead of one that's offered in their Suzuki book. With a slightly older child it might be allowing them to pick the order of what we do in a lesson from time to time, or the choice between learning one of two possible songs which offer similar skills.
Regardless, the teacher to coach transition usually starts with high schoolers needing to prepare music for an orchestra concert or first gig, or they simply start to become more vocal about pieces they like or don't like. With teens and adults, we have to think about how music can fit into their lives, to help ensure that it continues to fit at all. This can mean needing to work on orchestra music rather than solo repertoire, or picking battles between various techniques we want them to learn so that despite their busy school or work schedules they can still see progress and feel accomplished. If it's a student we've taught since childhood, this shift sometimes sneaks up on us, but we really should anticipate it around age 12-14.
We have to recognize that sometimes there's also pressure and expectations at school. It's an age where they especially want to do well amongst their peers, so even if the music is sometimes below their ability level, yes, they might want to work on it, just to be sure they won't embarrass themselves. They might have a concert coming up, or a regional or statewide school orchestra competition. Although of course we want them to continue with their solo work, scales, and etudes, all the student might be able to realistically focus on for a while is doing well for their school. It's quite understandable, as annoying as it can be as a teacher to have to switch gears for a while.
Of course, if a student is completely unwilling to do anything we say, then we have a deeper issue and would do well to have a conversation with them that addresses the teacher's expectations, the student's interest level and goals, and finds a compromise that can keep them going. I personally like to give them the chance to work with me before going to their parents, but that might also be necessary if the issues persist.
The balancing act as a teacher of teens and adults can be a tough. While helping them start to realize their own vision of where they want to go, we do need to continue to find ways to help them recognize the necessity of technical work and progressive repertoire. We can and should try to stay methodical, but at an age when many students, overwhelmed with high school academic and sports demands, may quit, or may soon be forced to set their instruments aside for college careers, it's worth working with them. As much as it would be nice to be able to force them to follow our program, I feel that our most important job is seeing if we can keep their passion for playing alive through their bumpy teen years.