Children do not enter classrooms as blank slates. They carry prior learning — sometimes accurate, sometimes flawed — and it shapes how they interpret every new lesson. If we ignore this, we risk teaching content that never lands.
Diagnostic teaching is the practice of continuously probing for prior knowledge, surfacing hidden misconceptions, and adapting instruction in real time. It shifts the teacher’s role from “What did I teach?” to “What did this learner experience — and what must now be revised?”
