Balls, plants, and flowers

The physical science students run a basic laboratory in which a ball is rolled. The ramp provides a mechanism for rolling the ball at a repeatable speed. The typical version of this experiment involves timing the ball to fixed distances from the bottom of the ramp. The laboratory leads to a linear regression.


The problem I have with the traditional method is that this makes distance the independent variable and time the dependent variable. The correct graph would be distance versus time, the slope of which is the pace not the speed. Physics typically graphs time versus distance, thus the slope is the speed.

While many instructors simply time to fixed distances and then graph the dependent variable on the x-axis, this does not work well when OpenOffice.org Calc or Microsoft Excel are the graphing tools. These packages cannot support multiple x-axes. Since we also roll the ball from half-way up the ramp, there is a need to have distances for pre-specified times.

The students use their sandals to mark where the ball was at one second, two seconds, three seconds, and four seconds. Then a tape measure is used to determine the distance to one second, two seconds. This creates an x-axis with common times for different ball speeds and ensures that time is the independent variable.

This version was conceived by me while sitting on the beach berm in Piyuul, Kosrae, during Christmas break 2007.



The ethnobotany students give presentations on the botany of seedless vascular plants. The seedless vascular plant lecture was at one time a 90 minute lecture that put the 3:30 P.M. class students to sleep. Nothing was learned. Having the students do mini-presentations means that less material is covered, but no one is sleeping.



A flower as large as one's head! A new variety of Hibiscus chinensis on the island. The flower is flatter than the typical H. chinensis and provides a nice, clean example of K5C5A8G5.