While it is true that instructors cannot know the schema of every student, for completely asynchronous programs or ones that have a synchronous lecture with hands-on labs later, assumptions have to be made. Since the instruction is prerecorded and the materials are prepared, how would an instructor be able to connect, observe, respond and adjust? The material talked about the need for this in online and in-person classes as well as synchronous and asynchronous learning, but it did not give many examples for the latter.
