### Acceleration of gravity

Laboratory 032 involves timing the fall of a ball to determine the acceleration of gravity g. The students drop a small superball from heights of 100 to 300 centimeters inside the classroom.
 MaryHellan, Ceasar, Leilani drop from the 140 cm range

Laboratory 032 now builds on two earlier activities that during a regular school usually occur on Monday and Wednesday respectively. The first activity was a plot of time versus distance for an accelerating RipStik.

The students graphed the time versus the distance for the RipStik and found a non-linear relationship (curved line) between time and distance for the accelerating RipStik.
 Norma performs a drop from 280 centimeters
In the second activity, the arc of a ball, the students explored whether the trajectory of a ball might be related to a parabola. A quadratic equation was presented as the underlying mathematical relationship. The students graphed their data and the equation to explore whether the ball arc and the equation were related.

These two activities built nicely into this laboratory where the specific mathematical relationship nature of time versus distance for a falling ball was measured. Put more simply, if a jacks ball falls twice as far, by what factor does the time increase?
 Moving outside, the class performs drops from 400 cm and 500 cm
A sample of the introductory notes on the board.

With the modifications made this term to the second activity which generates far more points for graphing, these two activities build nicely into this laboratory. Week three really feels like it has come together pedagogically.

Note that the summer approach of assigning teams to work at specific height was not deployed this term. Encouraging students to compare data between groups, and doing some comparison work myself, appeared to help correct timing errors. There were, however, as always, some groups that slipped past my attention and had serious timing errors in their data.