Friday, June 15, 2012

Oobleck-Glow in the Dark Style

Cornstarch and water...who would have thought? If you have never tried it, I don't care if you have kids or not, its cool. But add the element of glow in the dark? Forget about it! Its AWESOME. I got the idea here at Train Up a Child. There's nothing like a moving picture to show you what I mean. 


How do you do this? First to make glow water; empty the ink from a highlighter into a small amount of water (I should have used less water but it still glowed with the black light.) 


Slowly pour the glow water into cornstarch. While its roughly equal parts, error on more cornstarch than water. Enjoy the texture! Take your time. You'll know its just right when you can roll it into a ball in your hand, but it turns runny when you open your hand!






Then, using a Black Light, the Oobleck glows! Amazing! 


Now, the science of it all! Usually Oobleck is a referred to as a non-newtonian fluid. That is, it acts like a liquid when being poured, but like a solid when a force is acting on it. You can grab it and then it will ooze out of your hands. But technically speaking, the goo is a SUSPENSION, meaning that the grains of starch are not dissolved, they are just suspended and spread out in the water. So why does this concoction act the way it does? Most of it has to do with pressure. The size, shape, and makeup of the cornstarch grains causes the cornstarch to “lock-up” and hold its shape when pressure is applied to it. People have filled small pools with oobleck and they are able to walk across the surface of it (as long as they move quickly.) As soon as they stop walking, they begin to sink. (Science background directly from Science Bob.) 

If you let the goo sit for a while, the cornstarch settles to the bottom of the bowl. I also found out that you cannot store oobleck, it develops a foul odor. Consider it a one-time use activity, but the ingredients are cheap, so don't worry. When disposing of the goo, throw it in the trash, not down the drain! Imagine what that would do to your pipes! Not fun! 

Enjoy! 

4 comments:

  1. Wow I did not know that about walking across it! I feel an experiment coming on...
    Thank you for linking to my post. I'm glad to have found you! I'm now following via RSS.

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    1. Allison,

      I LOVE your blog and LOVE everything you do with Glow Water. I've got some of the water beads that's next on my list to make glow! Keep up the great job of sharing these wonderful ideas!

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  2. Dr. Harland,

    I was so excited to read your post!! I am a former university student of yours and I now teach Kindergarten at a STEM elementary school. We have STEM camp this summer and made oobleck yesterday! I'm excited to share the glow-in-the-dark idea with my colleagues. We also made a really cool slime using borax and glue with a little food coloring. Thanks for posting your ideas-even for kindergarten they are FANTASTIC!

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    1. So glad you found me! Since my son is going into kindergarten, I take everything I do with high school kids and bring it down to his level! But it is not always as easy as I'd like it to be!

      A STEM elementary school? COOL! I'd love to hear more about it. I've visited your blog before, I'll keep tabs on you, ok?

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