Electronic Proceedings of the Seventh Annual International Conference on Technology in Collegiate MathematicsOrlando, Florida, November 1720, 1994Paper P021
The Rule of Four in a TechnologyEnhanced Precalculus Course 
Lynn Foshee Reed
Virginia Polytechnic Institute and State University
Blacksburg, VA 240610123
USA
 Susan Hagen
Virginia Polytechnic Institute and State University
Blacksburg, VA 240610123
USA

Studying families of curves through transformations, analyzing
data, writing, and the TI85 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 TI85'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, TI85, modeling