How to Make Gak – with Help from The Teacher!

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My husband had a great idea to do with the kids- perfect for sensory experiences and hands-on coordination! Not to mention just plain fun! Although I call it oobleck, The Teacher calls it GAK! This is a fun experiment which helps younger children to understand the difference between solids and liquids.

Materials Needed:

  • Cornstarch

  • Food Coloring (optional)

  • water

  • bowl and cup

  • spoon


Have your child scoop some cornstarch into a bowl. Set aside. Then have a cup of water with any choice of food coloring desired. Let the child add some food coloring to the water- encourage them to find out what happens if they mix colors too!
Then pour equal parts of water into the cornstarch bowl. Mix thoroughly making sure there are no lumps. 
The consistency should be smooth and slightly runny but not watery. There should be no lumps or thickness to it. You may need to add a little more cornstarch or colored water to get the desired result.
Now the fun thing with this gak is that it is a non-Newtonian fluid. If you slowly put your finger (or use a spoon) down through the substance it will stick to your finger and make a mess, just as if you would dip your fingers in a glass of water (fluid). But if you poke rapidly at the substance it will become hard (solid) as a rock, and you will not get messy at all!  
I used to love “wowing” school kids with this experiment- although it can get messy quickly! You can pour your GAK in a plate, bowl, on the table, or even keep it in a cup. But you need to throw it away when you’re done as it will not maintain it’s properties- and don’t throw it down the sink!! It can separate can clog your drains!

Ideas of topics to discuss with your science fun depending on the age of the child:


  • Non-Newtonian fluids

  • solids/liquids

  • viscosity

  • the color wheel

  • properties

  • chemical/physical changes

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  1. cathy graham says:

    love this! My first graders love it too! We call it goop!!

  2. cathy graham says:

    oh, put a little white glue in it and it makes their own "flarp"—they love it!

  3. Melissa + Tiffany @ Home Grown Families says:

    Great idea! I also left you feedback over in CBias! !I am going to do this with my little ones! Thanks for sharing and being part of Bloggin Social Facebook group!

  4. Linda @ Linda's Lunacy says:

    We made this several years ago, and all the kids loved it. Even the teenagers. lol Did you know if you put it in a big enough container, you can stand on it? Or sink if they are not careful. lol Remember to put newspaper on the floor first!

  5. ldybug1682 says:

    So awesome!! I'd love to link to this post on my page sometime. I love these creative ideas!!

  6. We made this last year, I didn't even think of coloring it. The girls loved it and I think we will do it again in the near future.
    Thanks for sharing.

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