The Rule of Four in a Technology-Enhanced Precalculus Course

Lynn Foshee Reed

Virginia Polytechnic Institute and State University
Blacksburg, VA 24061-0123
USA

Susan Hagen

Virginia Polytechnic Institute and State University
Blacksburg, VA 24061-0123
USA

ABSTRACT

Studying families of curves through transformations, analyzing data, writing, and the TI-85 graphing calculator combine for a precalculus class centered around the Rule of Four. This poster session will display student work from precalculus classes at Virginia Tech. In our illustration, students looked at data from the mile run and were asked to find an appropriate model for the data. After identifying possible families of curves which fit the data, the students found one model's equation using the technique of transformational movements. They also used algebraic techniques to find other potential models of the data. Using the TI-85's statistical features, students determined various regression equations for the data. By comparing vertical distances between the models and the actual data, students justified which model was the best fit. Lastly, the students used their chosen model to interpolate and extrapolate the data to find answers to questions about the mile run. The focus of these and similar exercises was as much on getting a numerical answer as it was, 'Does the answer from the mathematical model make sense in the problem context?' The use of journals rounded out the exercise as students wrote about the modeling process.

Keyword(s): precalculus, TI-85, modeling