Learning progressions (LPs) gained popularity and importance in the science education field to guide curriculum designers, teachers and researchers as a useful tool to bridge between curriculum, instruction and assessment. Although teachers' professional development can be built through learning progressions these LPs do not describe the ways that teachers can improve as practitioners to scaffold student learning. Research-based, five-step Formative Assessment Design Cycle (FADC) is an iterative professional development cycle which helps teachers to design and effectively use of formative assessments in classroom settings. Within this context, this paper investigates senior biology student teachers' modern genetics knowledge before and after a formative assessment design cycle (FADC) program based on learning progressions.