This is my first post on Pianostreet, but I felt compelled to register and write a reply to this forum message.
First off, I have a performance degree from Oberlin Conservatory in classical piano, and have spent the better part of my professional career both teaching and composing. In addition I perform jazz, salsa, and pop music. I only mention this because I have experience on "both sides of the fence".
I understand the frustrations of students who want to learn other music. I was one of them. When I was about 10 or 11 I was enrolled at the Peabody Preparatory division. I got a pedantic Russian-school teacher who was unwilling to let me play anything beyond a narrow band of student-level classical pieces. They are what I now think of as the really mediocre Sonatinas by Kuhlau etc. We all assign them, and speaking as a composer I can say that they mostly pretty uninspired works of music, frankly.
I wanted to learn some jazz. No, I didn't want to study improvising, I just wanted some music that sounded jazzy. There are lots of books of jazz/pop music by educators and performers. A series by Oscar Peterson comes to mind. Unfortunately my teacher wouldn't budge. I nearly walked away from the piano. At my audition for the Peabody program I couldn't be STOPPED from playing all the little pieces I knew. In less than 6 months, she took this 10 year old boy to the point where he wanted to walk away from music and music lessons.
Fortunately, my Mom had the foresight to get me with another teacher. The first thing she did was to get me some old Boogie-woogie sheet music, and light pop/jazz arrangements of things like "I'm in the Mood for Love". It was hardly Gradus ad Parnassum, but it was exactly what I needed at that moment to sustain my interest. This was also around the time I learned some Joplin rags. By the time I moved away from this new teacher I was practicing Brahms Rhapsodies etc. and was getting much more serious about classical music.
I also remember a few times later on where I insisted on wanting to learn other pieces, including a Mozart Sonata. My teacher didn't want me to, but I learned it anyway. Never underestimate the power of personal motivation to push a student to learn. They will likely try to learn the piece, whether or not you want to help them. I think it's better to engage the student, and incorporate some of what interests them.
As pianists with classical backgrounds, we tend to forget that the world is filled with, mostly, POP music. The fact that your original post misidentified Taylor Swift as "Taylor Smith" and One Direction as "New Direction" is very telling, especially since Swift is such a major figure in the pop music world, irregardless of what you might think of her musical abilities. These artists and music are what defines these kid's musical world. When I run across older students who want to learn this sort of stuff, which is invariably very simple structurally, I either do a quick transcription of some of the melodic material, or I look for a source for sheet music.
I run across so many adult students who were psychologically scarred by rigid pedagogy. As a piano teacher, I feel it is my job to instill a love of music and performance. I need to get my kids to count, have better rhythm and timing, and hopefully to use dynamics occasionally. "Do no harm", i.e. make sure they continue enjoying music, and hopefully get at least a little appreciation for music that is performed by real people on real instruments. In a few years, if you can keep her motivated, you may find her naturally moving towards more serious repertoire. Ultimately, more piano students are going to lean towards Floyd Cramer or Willie Nelson, Taylor Swift or Beyonce, than they are towards Schumann and Bach. And they're allowed to.
Topic: Thinking about dismissing a student