Note that if you use a computer, some programs will not allow you to set the scale for the y axis such that it goes from a positive number at the bottom to a negative number at the top. A rise in points on the graph indicates a rise in brightness, so inverting the axis would make the results counterintuitive. The students will give their estimate to their teacher as they collect them, who will write down the Observer Code with the estimate. Students are not to tell their estimate to anyone until the day's estimates have been collected, to prevent others from changing their estimate. The teacher will plot all of the estimates on a single graph.
Students are to look for trends in their own points and trends in the points plotted by the class.
The data for the class will be compared to the ICQ estimates . The scatter in the points in both cases can be investigated. It turns out that bias and making comparisons betwen stars and comets are both big problems. Some points will appeared clustered, others will be noticably different. Compare the sketches and other visual observations to the magnitudes.