The second role of the instructor during class time is to provide feedback to students.
These teachers are continually observing their students and assessing their work during the class activity. Students are allowed to make and explore their mistakes, but the instructors are there to redirect them if they deviate too far or are getting frustrated. Teachers can also identify individual students that may need extra attention and provide individualized, directed instruction in real time.
These ongoing formative assessments can also be used to inform future instruction. If the teacher notices that a large proportion of the class has difficulty in one area, this gives that teacher important feedback on their pre-class modules. Modules can be modified to better address the troublesome areas.