In addition, regardless of which instrument is used to measure the period of the LED, either a frequency-meter or an oscilloscope, we recommend that this measurement be carried out in a large group setting prior to the start of the experiment. Finally, it may be interesting for students to explain why the falling LED produces bright lines in the photograph, even though it is essentially a point source. And why should the length of these bright lines increase as the LED falls? This sort of qualitative discussion is often left out, yet it is an invaluable part of the learning process.