In this clip the teacher leads a discussion about what makes a situation exponential.
Introduction to Exponential Functions, Clip 6, 2:02
The teacher is taking this opportunity to discuss the changing rate of change that occurs in exponential functions. This is only the 2nd day of the exponential model, but it is useful to contrast exponentials with what they have already learned, such as linear functions.
The teacher makes sure to push the students and to encourage them to use the terminology for the class. For example, notice how the conversation continues until they discuss exponentials as having a constant factor.
The teacher also asks them whether or not all graphs increasing at an increasing rate are exponential. It is common for functions that are increasing at an increasing rate to be described as exponential when that does not have to be true. This is a discussion that can be started here and continued as the module progresses.
