By exploring "the trumpet" as a metaphor, a successful mid-career instrumental teacher and a teacher educator jointly conducted a narrative inquiry into pedagogy used with a high school composition class. In particular, they focused on the dilemmas that arose when, within this class setting, the instrumental teacher implemented informal learning practices for the first time. This teacher struggled as he shifted from the teacher-directed pedagogy he employed in concert band instrumental instruction, to the social-constructivist pedagogy he felt was required of the composition class. As he began implementing informal learning practices, this teacher questioned both the value of his identity as a classical musician and the effectiveness of social-constructivist strategies, finding dialogue and small-group problem solving to be an inefficient use of class time. Despite these struggles, or because of them, he grew as an educator. Based on these findings, it is suggested that teacher educators should consider addressing the complex challenges to identity and epistemology that initial engagement with informal learning and social-constructivism may elicit from practicing and pre-service educators.