Responding to "I Don't Know"
When we let students use "I don't know" as an answer, we allow them to opt out of answering the question. Even when a student truly does not know the answer, we can still encourage them to attempt an answer. From there, we can praise their effort, and then call upon another student to help finish the answer. Norm for your class that "I don't know" as a response will be respected, but not be accepted. Norm that every student must attempt to answer the question and be okay taking that risk.