Doppler Shift

I was chatting with my mom today and realized that I hadn't posted videos of me creating the doppler shift yet! How that happened, I have no idea. These videos are something the world really needs to see. Really.
It all started with me taking a Technology in the Classroom class for my major. One of the assignments was to make an instructional video. I decided to do mine on the Doppler Shift (also known as the Doppler Effect) because it would be easy.
It just so happened that my family came down to Provo to visit me the very weekend that I needed to film. So they got roped into helping me (although honestly they loved it).
So, for those of you who don't know what the doppler shift is, let me explain it to you.
First of all, sound (although this happens with light too, you probably won't really see that if you are an astronomer). Sound is a wave. So it has peaks and valleys, or crests and troughs, or whatever. The distance between peaks (also known as wavelength) determines the pitch we hear. The closer together the peaks are, the higher the pitch.
The doppler shift happens when either the source of a sound is moving, or the person hearing the sound is moving. Let's chose the first case, where the source is moving. So imagine an object producing a sound--a wave--that is radiating all around it, with peaks evenly spaced. If that object starts to move, by the time it releases the next peak, it has caught up a little bit with the peak it had already created in front of it. This effectively makes the distance between those two peaks shorter, meaning the wavelength is shorter, making the pitch higher.
The reverse effect happens behind the object because it is moving away from the peaks it had already created, making the pitch sound lower.
A very similar thing happens when the person hearing the sound is moving toward or away from the source of sound for the same reasons.
I'm sure you are all at least slightly familiar with this effect because you hear it all the time. Make the sound of a car speeding quickly past you. What does it sound like? VAAA-roooommm (higher pitch while it is heading toward you, lower pitch while it is heading away from you).
Anyway, now that you have had your physics lesson of the day, my videos.
We tried to create the Doppler shift several ways (admittedly, some of them just for fun). The last video is of when it actually worked.
Enjoy my silly family. :)
(oh, by the way, yes, that is a kazoo. Also yes, that is a Creamery on 9th shopping cart.)