Friday, August 24, 2012

Dancing Oobleck

We had a blast on our first day of school learning about sound waves with "Dancing Oobleck."

Our first attempts to make this experiment work didn't turn out too well.  But, Daddy was persistent and we eventually got the result we were looking for!    Plus, by having to be patient, keep trying, and be flexible enough to make adjustments, the kids got a bonus lesson that wasn't even planned.  How's that for keeping a positive outlook? ;)

Here is the video of our "Dancing Oobleck."



Much of this information is in the video, but just in case you didn't catch it, here is how it works.  First, you will need the following supplies:
  • Cornstarch
  • Water
  • A metal cake pan or cookie sheet.  You want it to have a pretty smooth surface.
  • A speaker that can be hooked to a computer
  • A sound wave generator program for the computer (Type "sound wave generator" into a search engine to find one to download.  There are several free one's out there.)
The cornstarch and water will be used to make oobleck.  If you remember, we made oobleck for our science experiment last year.   This experiment uses it again.  Here is the recipe:


Oobleck Recipe
  1. Mix 1 part water with 1 1/2 to 2 parts cornstarch. You might want to start with 1 cup of water and 1 1/2 of cornstarch.  You can then work in more cornstarch for a more "solid' oobleck. It will take a bit of mixing to get it to the right consistency
  2. Mix in a few drops of food coloring if you want colored oobleck.  (I chose not to do this because I didn't want everyone to have colored hands.  It was just as much fun without it.)
Place the oobleck in the cake pan/cookie sheet.  You can actually mix it directly on the pan.  Place the pan on the speaker.  Turn on the sound wave generator.  You will want to try out different tones, but 120 hz is a good place to start.

If it doesn't work right away, don't give up!  It took a lot of trial and error before we made this video! The instructions I found online weren't very detailed, so hopefully this tutorial will save you from making some of the same mistakes we did!

Tips:
  1. Lay the speaker so that it is facing up and is level.  If it is slanted at all, the oobleck will tend to slowly move in one direction.  We had to shove something under one end to get the speaker completely level.
  2. Remove anything blocking the woofer (the actual speaker part).  We used my husbands PA speaker that has a grate on the front to protect it.   We eventually figured out that too much of the vibration was escaping in the space between the woofer and our pan.  We removed the grate and set the pan directly on the woofer and immediately got better results.  A smaller speaker might have worked better.  But, we used what we had.
  3. You may need to hold the pan still while conducting the demonstration.  If you look closely at the video, you can see that I am holding the pan with one hand.  Otherwise, it just vibrated right off!
  4. You may need to experiment with different consistencies for the oobleck.  If it doesn't work at first, you may need to add water so it will be thinner or add cornstarch to make it thicker.
  5. If the oobleck starts to spread out, away from the center of the woofer, you may need to move it back.  You see me doing this several times in the video.  
  6. I noticed that when I did move the oobleck, it helped start the movement, too.  So, if nothing seems to be happening, you might want to push the oobleck around a bit.
If you try this out, I would love to hear how it goes!  Hopefully you find my tips helpful and you have as much fun as we did!


4 comments:

  1. does this even work

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  2. Very helpful - thank you for posting!

    ReplyDelete
  3. I like this, I am planning on using this in my class.

    ReplyDelete