Abstract: This preliminary research project grows out of a long-standing practitioner effort to design and implement proof instruction in which students’ understanding of quantifiers is built on their prior skills with the logic built into the casual language that they use outside of mathematics classrooms. While this previous work has elements of design research, it was approached as applied scholarship and practitioner work rather than basic research. However, I am now in a position to describe empirically-derived hypothetical learning trajectories for student thinking in this approach to proof instruction. This preliminary talk will share work in progress for these learning trajectories.