In this clip the instructor discusses the where the multiplicative factor comes from in an exponential function and how it works as the input is increased by 1 year.
When the group gives their solution to the above problem, the teacher writes their suggestion on the board to create a discussion.
Multiplicative Factor, Clip 1, 5:21
By writing the students' solution on the board, the teacher has something that is observable by the other students. This creates the opportunity for a discussion about whether or not it is a correct solution.
Notice how she reinforces the appropriate terminology and makes a point of saying that whta they have is a 3 year growth factor.
The teacher also presents the students with an alternative way to approach the problem that did not emerge from the student contributions.
This leads to a discussion about why it is not 21% (a common student answer). They continue this discussion until the students use the terminology of the classroom. To do this the teacher asks a student to restate “in your own words” the response of another student.
