Two useful observations are possible when thoroughly looking at the cathode-ray display of a computer. First, the structure of a color image is seen with a moderate magnification. Second, the decay of different phosphors corresponding to the red, green, and blue primary colors is observable with a photodiode and oscilloscope.

This article introduces a new computer conferencing metric called Scan Rate, which is a measure of students' and instructors' online reading speed. The term "scan" refers to the practice of either skimming through a message at an unusually rapid pace or reading a message partially and then stopping before the end is reached. It is…