Repeat for the highest score. Connect these two lines with a vertical line. Use dots or small circles to represent outliers. This is a display of the range of scores for the class for that measure. Be sure to use the median rather than the arithmetic average for the central point.
Averages are less stable and can be drawn up or down by outliers.
Darken the vertical range line between the 75th and the 25 th percentile. Repeat the process for subsequent measures. The aim line is a guide to help you gauge the progress of your class. It is not intended to represent a rigid benchmark. Interpreting the visual display is relatively straightforward.