This song explains how the decay of a radioisotope has a half-life and how to use that half-life to solve decay problems. Corny but clear science. May appeal to some students!

Instructor Blaine Greenhalgh explains the doppler effect. Good animation of man walking with a light globe.

The Doppler effect (or Doppler shift), named after Austrian physicist Christian Doppler who proposed it in 1842, is the change in frequency of a wave for an observer moving relative to the source of the wave. It is commonly heard when a vehicle sounding a siren or horn approaches, passes, and recedes from an observer. 

In the last physics lesson, the teacher seemed to have to explain the Doppler effect for quite a long time to some people before they understood it. So, being the nice, considerate, thoughtful person I am, I decided out of the goodness of my golden heart to explain the Doppler effect for future reference using animation (actually, I thought it would be a fun thing to do anyway). For those of you who are confused about what the Doppler effect has to do with anything, it's red shift and blue shift. So it is relevant to the lesson.

Following the earthquake and tsunami in Japan, we discuss what is causing problems at the nuclear reactors in Fukushima. Explains the relevance of hydrogen, iodine, boron and zirconium.

Japan's Nuclear Crisis Explained in Four Minutes with clear graphics about the workings of the reactors.