Discuss Multiple Trials and Average. Discuss how many trials should be made for each height.
- Why should you do multiple trials? (To account for error. So much can go wrong in any experiment that repeated measurements are crucial.)
- What is considered a bad trial? (When the car rolls off the side of the ramp, or runs into the side of the ramp or off the side of the ramp)
- What should you do with a bad trial? (Bad trials should be discarded. All measurements for trials with the same height should have distances that are close to one another.)
- Should you find an average of all these trials? (Yes)
- What sort of average? Median, mean, or mode? (Median probably is best, since we have not done many calculations with decimals yet and mode is only useful for more data points.)
- Look at Question 9B. Why is taking an average a good idea? (Due to small errors, we average the data to get the most accurate result; averaging reduces the effect of random errors we cannot control.)
Discuss Ordered Pairs. Refer students to the data table shown in Question 9 in the Student Guide. Note that the table allows for three trials, an average, and the ordered pairs. Remind students how they used ordered pairs to help them graph the data they collected in the Bouncing Ball Lab in Unit 5.
- How does the data get represented in the ordered pair? (The manipulated variable (H) goes first followed by a comma and then the responding variable (D).)
- You collected more than one distance. Which distance do you use in the ordered pair? (The average of the distances collected.)
Once students are ready, ask them to collect and organize their data (Questions 9).
Observe students collecting distance data in Question 9 in the Student Guide to assess their abilities to measure length to the nearest hundredth of a meter [E4].
