I usually introduce this one just by telling students that we are going to make a craft project. We spend about 5 minutes snipping at soda straws, and then I show them how you can make the straws squeal by blowing into them, and the students have a blast. At the end, we discuss how oboes and saxophones work in the same way as their soda straws. What they made was essentially a soda-straw oboe.
To make a soda-straw oboe, you simply cut a pair of "reeds" into one end: Flatten one end and crease the sides as best you can, then snip away the corners, making two pointy triangular flaps, like this:
The exact size and shape of the flaps isn't critical, but they should be reasonably symmetric and not too short. They should be maybe 1½ to 2 times longer than they are wide. Also, I have found different performance with different brands of soda straw. The plastic in some straws is a little firmer and harder to crease, and those straws don't work quite as well.
To play the oboe, you place the reeds inside your mouth and pretend you are biting down on the base of a duck's bill. With your teeth or your lips, press the bases of the two flaps close together, and then blow as hard as you can. Depending on the flexibility of the plastic, and on how you shape your mouth, you may be able to produce a variety of squawks and squeals.
When I would try this activity with my classes, there would often be a few forlorn children unable to produce the sounds and have all the fun that everyone else was having. I can't guarantee that every child will learn how to make the noise, but I can offer a few tips:
- Children often make their flaps or "reeds" too short and stubby, in which case they probably won't vibrate well. The triangular reeds should be longer than they are wide. The shape shown in the photo usually works well for me.
- You need to clamp down with your mouth to flatten out the end of the straw, but you still need to allow the reeds to vibrate. Sometimes children will clamp down on the reeds themselves, and prevent them from vibrating. They might need to insert the straw a little farther into their mouths.
- To make the oboe sound, you need to blow pretty hard. Sometimes just telling children to blow as hard as they can works. Another suggestion that sometimes helps is to clamp down all the way, closing the straw, then try to blow hard, building up air pressure, then very gradually release your grip on the straw until a tiny stream of air can get out.
In my experience, the novelty of noise-makers wears off pretty soon unless you can actually play different notes. How can we make our straw oboes play different notes? I have tried fitting a second, ever-so-slightly larger straw over the first, and making a "slide-oboe", but the two straws have to be very close-fitting or it doesn't work. I (and my students) have also tried snipping holes into the sides of the straw. We can't play recognizable melodies, be we can at least make different notes come out by uncovering one or the other of the holes. (It is only the closest opening to the mouthpiece that matters, so it doesn't do much good to leave them all uncovered and cover them up one at a time.)
If you wish to demonstrate how actual reed instruments work, you probably won't want to buy an entire saxophone just for a science demonstration. However, you can buy a saxophone mouthpiece for only a few dollars, from Amazon or from your local music supply store. It isn't too hard to learn how to make it squawk all by itself, or you can attach it to a length of garden hose or a hollowed-out carrot, as Linsey Pollak has done.