How to conduct formative assessment in K-12 to see if students have truly mastered the material

When I conduct formative assessment in K-12 classrooms, I no longer treat quizzes as just a score sheet. Scores only tell me who got it wrong, not why. Now, I break down a lesson's objectives into two or three observable actions, such as whether they can explain a concept, apply it independently, or identify exceptions. I use one-minute exit tickets in the middle of class; I don't aim for a high…