Wave Frequency Experiment

In the Science Storage Room of Magic (SSRM), I found these the other day:

BoomWhakers, pic taken from http://boomwhackers.com/

I pulled them out an hatched a plan.  As a follow-up lesson to our frequency and amplitude lesson, I decided to do a little experiment. This was both to let the kids experience these properties more, and to give them more practice on the hypothesis and conclusion writing (see this post).  I gave them the question.

The Tube Experiment

Question: How does the length of the tube affect the pitch of the sound?

Hypothesis: I hypothesize that an increase/decrease in ______ will increase/decrease the ______.

Experiment: We all took a tube and stood in order of longest to shortest.  We then took turns sounding the tube, starting with the longest tube.  We listened to the sound.

Conclusion: My hypothesis stated that __________. My results do/do not support my hypothesis.  The results show ___________, because ___________.

And that's the basic write up that they did.  Simple and easy.  Remember, I'm in middle school and sped. But we still do it correctly.

After sounding the tubes out, we had a discussion on what the results showed (i.e. an increase in length decreased the pitch, or a decrease in length increased the pitch), and why.  The why was a little confusing for them, but that's more advanced.  All they need to know is that what differs between each tube is the frequency of the wave. 

If you don't have BoomWhackers, then try this experiment.

BE WARNED: 

(1)It's cool, but because it's cool parents and waitresses/waiters everywhere might be forever frustrated.  

(2)It will also create a mess in your classroom. 

(3)Also, this might be good to do at the end of class after all instruction for that day. Otherwise you'll hear annoying noises for the rest of class.