It has been a while since I have posted due to my laziness in this area. I did have a few things going on since my last post and I am working on getting those down. But we have done something recently that I really wanted to talk about.
In class we have been working with waves. Mostly sound. We started the unit with an experiment using a set of electrical conduit cut into different lengths and figuring out the "sweet spot" (node) where we could hold the pipe to have it ring the longest. (~23% from one end) Then we did a little experimentation to find that any uniform length had the same ratio. While we were looking at this phenomenon, I asked the students to post in a discussion board what questions they would like answered that occurred to them during the experiment. That way we can make sure to try to get them all answered before the end of the unit.
This experiment led to a question about the tones in the pipes vs. length of pipes. We experimented some more to find out the period of oscillation vs. the length of pipe. (T is proportional to L^2) Then we moved into standing waves on strings and air columns. That needs a bit more work but I would like to try something like this: http://evanweinberg.com/2012/04/11/stand-up-and-wave/ from Evan Weinberg. (I feel my sequencing is off.)
After we did some spectral analysis of musical instruments, we announced the musical instrument project. Our basic criteria was that it had to contain an octave and play "Mary had a little lamb". There was a variety of instruments, but, unfortunately, a lot of people went back to what we looked at in class and made modified pipe glockenspiel. We really wanted to see something that was more innovative and imaginative, and we did get a lot that were not what we had seen in class. One of the best was a player glass harp. They connected a spoon to a bar that rotated and the spoon struck a set of glasses filled with different levels of water and made the different tones. We also got a variety of stringed instruments and bottles of water. 2 or 3 pan flutes as well as a PVC flute. A couple of groups even used rubber bands to create their vibrations. They all had to present their instruments and play at least one song on them but most played several songs.
Being a girls school we did have to deal with a lot of "pretty" projects and that distracted them from the physics a bit. They were also given three weeks to complete the projects which, for some, was more than necessary and gave them more time to make it pretty.
In the future, I would like to see them complete the project in less time in order to focus more on teh physics of the project, but they were getting stressed out so we had to back off and give them an extra week. I don't think they really understood how much time it would take to get the instrument build and tested. Many had to cut pipe a second or third time in order to properly tune their instrument. That was one of the requirements was that it had to be in tune, we reasonably. I could never tell because I could not carry a tune in a bucket. During their presentations, we asked all sorts of questions from their inspiration to how they tuned their instrument.
What I found disheartening was the fact that so many of the projects were made from pipes, which is what we spent so much time on in class. The students didn't really stretch themselves and try to come up with anything very interesting in terms of what they could use to make the music. I was really hoping for more of a range of projects.
If you are so inclined, you can see our handouts here. There is a description of what we expect, a project proposal form, and a project summary form.
A couple of Pan Flutes.
A metalophone made from electrical conduit.
A PVC Flute with their sheet music.
An interesting guitar. I am not sure they really understood the meaning of the bridge, as it ended up on the end of the neck.
Rubber band dulcimer? Sounded OK when you were really close. The sounding board was not directly connected to the strings though.
Here are a couple of fanciful ones that didn't really do anything. I think they were going for style points.
More style points here but they ended up getting a working instrument.
