Motivated illusion of transparency
The motivated illusion of transparency refers to a situation where the teacher, consciously or subconsciously chooses methods to minimize evidence that the learner may not be following. This may, for instance, include an avoidance of cold calling in large class settings. It may include asking bad diagnostic questions (cf., double illusion of transparency). It may include the use of perfunctory "questions or comments?" prompts.
The main motivation behind maintaining an illusion of transparency is that it reduces the tension between helping the learner understand and following the planned schedule (such as the class script).