Healthy KidsYMCA Camps and Outdoor Education

A science experiment to keep your kids learning at home

02 April 2020 - by YMCA of Greater Toronto
We get it: keeping your kids entertained and engaged gets tricky when you’re trying to stay in as much as possible, and don’t want to let them sit in front of the TV/tablet/smartphone all day. Pique your budding scientist’s interest with this simple experiment you can do with stuff you probably have in your kitchen. It’ll teach your little one about sound waves, and how sound can impact matter through vibration. Plus, they get to get their hands a little gooey, and we all know how much of a kick they’ll get out of making a little mess!

First: a mini lesson on how sound works

Sound is a vibration, or wave, that travels through matter (solid, liquid, or gas) and can be heard. The vibration is started by some mechanical movement, such as someone plucking a guitar string or knocking on a door. This causes a vibration on the molecules next to the mechanical event (i.e. where your hand hit the door when knocking). When these molecules vibrate, they in turn cause the molecules around them to vibrate. The vibration will spread from molecule to molecule, causing the sound to travel.

Sound must travel through matter because it needs the vibration of molecules to continue. The matter that transports the sound is called the medium. The speed of sound is how fast the vibrations pass through the medium. The type of matter has a large impact on the speed at which the sound will travel. For example, sound travels faster through water than air, and it travels even faster through steel.

Here’s what you’ll need for this experiment

  • Mixing bowl

  • Measuring cups

  • Two cups of cornstarch

  • One cup of water

  • A thick metal cookie sheet with a rim

  • Food colouring

  • MP3 of audio test tones (You can download and play different test tones to see what works best for you. (40 Hz, 50 Hz, 63 Hz.) To get ours, we did a search for “subwoofer test MP3,” and found, but there are tons of similar sites you can use.)

  • A speaker

What is oobleck?

Oobleck is a non-newtonian fluid: basically, a sort of slime that acts like a liquid when you pour it, but like a solid if you grab it and squeeze it in your hands. (Check out our video if you want one of our YMCA Camp staff to walk you through making your very own oobleck in real time!)

Here’s how to make your own oobleck:

  1. Mix together the two cups of cornstarch and one cup water in the mixing bowl

  2. Transfer the mixture to the cookie sheet

  3. Optional: add the food colouring to spruce your oobleck up!

  4. Carefully place the cookie sheet onto the speaker. Put your fingers on the edge of the cookie sheet, with gentle pressure, to keep it stable.

  5. Press play on your test tones! If your oobleck isn’t dancing, try changing the volume, or dig your finger in to get it going.

We hope you have as much fun trying this experiment at home as we do at YMCA Day Camps! Let us know how it went @YMCAGTA.


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