As K-12 computer science (CS) education expands, there is a growing recognition of the need for formative classroom assessment practices.Grover's recently developed formative assessment framework for K-12 CS provides guidance, however tools for evaluating formative assessment remain a gap-as evidenced in feedback to our formative assessment literacy PD efforts.This paper examines the suitability of Pellegrino et al.'s validity framework for instructionally relevant assessment for use in K-12 CS classrooms and teacher PD.