The present study examines the development of a specific sub-skill for studying and improving teaching—the generation of hypotheses about the effects of teaching on student learning. The authors compared between two groups of elementary preservice teachers (PSTs): one group that attended a typical mathematics-methods course and one that attended a course integrating analysis skills for learning from teaching. Findings reveal that PSTs at the beginning of the program struggled to generate hypotheses with relevant evidence, often equating teacher behavior or student correct answers as evidence of student understanding.