We report on one teachers' efforts to re-design an entire instructional unit as a coherent storyline about forces and motion as a part of a multiyear professional development (PD) project around the NGSS. Designing coherent storylines demands that teachers create opportunities for students to meaningfully engage in science practices in order to develop their knowledge over time. We found that appropriately framing the unit, lesson, and/or activity supported students take on roles as epistemic agents and sensemakers, whereas unclear framing led to more traditional roles for students that resembled didactic science teaching. This suggests that a primary issue for PD is to help teachers look at and plan how they intend to frame lessons/activities as a way for them to promote coherence and epistemic agency.