In this clip the teacher is leading a recap discussion with the whole class.
Meaning of Average Rate of Change, Clip 3, 2:09
The teacher leads a whole class discussion about the worksheet to make sure the conversations she had with small groups are heard by the whole class.
She makes a point of emphaszing that they are dealing with time and distance intervals, not single points, this is a crucial part to understanding average rate of change.
She also informally gets them thinking about the mean value theorem by having them deal with the question of whether or not they ever achieve their average speed. While instantaneous speed and the mean value theorem are not large components of this class, discussing them informally this way will help students understanding of average rate of change.
