Ask your class to measure their hand-spans in millimeters. Type in the results into the spreadsheet column. This will calculate the actual mean.
Suggest a quicker way to collect the data would be to record it in a grouped table. This time slide the first slider over a bit to reveal the tally column ask for hands up of students with certain hand-spans with reference to each group. Record a tally for each group (using a pen if projecting onto a whiteboard or a write-over application with a IWB). Slide across the sliders to reveal how to estimate mean from a frequency table and how the formula works.
Why is the estimated mean different to the actual mean? What are the advantages/disadvantages of the two data collection methods used?
