Student teachers struggle to identify themselves as teachers in their field placement during their student teaching year, and some of the difficulty can be attributed to the change they encounter when they must communicate scientific ideas to students in a language that differs from how they recently learned science at the university level. Using developmental levels of student teaching (Drafall and Grant in "Music Educators Journal," 81(1), 35-38, 1995), we explore how three cases differ in their use of verbal classroom discourse over the course of their student teaching year. We use data from six observations, post-observation debriefs, reflections associated with the observations, and responses to assignments from the student teachers' teaching classes as data to demonstrate how the cases differ in the proficiency of their verbal communication in their classroom placement. We find that when student teachers have difficulty communicating science to their students, they struggle to use lectures effectively or engage students in meaningful conversation or questioning. This work suggests a need for more study as to the causes of different communication proficiencies and how methods instructors can help teachers develop awareness of the value of their verbal discourse interactions with students.