Fun with Non-Newtonian Liquids: Liquids That Act Like Solids

liquidHere’s a slippery slimy activity to do with the kids for the month of April Fool’s: make a liquid that acts like a solid.

Non-Newtonian liquids are liquids that act like solids when pressure is applied to them, and you can make one with just two ingredients from your kitchen: water and corn starch.

Materials

small pitcher of water

measuring cups

molasses

corn starch

food colouring (optional, add it to the water if you want a coloured mixture)

two plastic trays or baking trays with a lip

Method

Begin by looking at how different liquids move.  Pour 1/4 cup of water from one container to another.  Pour 1/4 cup of molasses from one container to another.  Both are liquid, but water moves faster because it has a lower viscosity.  Ask kids to name the things in the house that act like water (vinegar, juice, milk) and the things that act like molasses (shampoo, ketchup, syrup).

Make your non-Newtonian substance by mixing 1 cup of corn starch with about 1/2 cup of water.  Gradually add the water to the corn starch until you have a mixture that pours like honey.  Pour this mixture from one container to another and observe how quickly it moves.  Is it more like water or molasses?

Ask kids to predict what will happen if they squeeze the mixture?  Will it run through your fingers?

Now scoop some of the mixture in your hands and squeeze it.  The harder you squeeze, the more solid the mixture becomes.  Force makes the liquid act like a solid.  Now stop squeezing.  What does the mixture do?

Pour enough water onto one of your trays to make a thin layer of water from edge to edge.  Ask kids to predict what will happen if you bang your hand onto the tray.  Splash!

Now do the same thing with the mixture on the second tray.  Will the mixture behave like the water?

Hit it and find out!  (There is a video here of the experiment if you want to see it before you try it in your own home!)

Experiment with different ways to exert force on the mixture: touch it softly, quickly, stir it slowly, hit it with the spoon.  You can even hit it with a hammer.

Clean up

This can get a bit messy, especially if you are using food colouring, so be prepared to wipe up spills and splashes.  Also, DO NOT POUR YOUR MIXTURE DOWN THE DRAIN.   It will clog your pipes.  When you are done, scrape your mixture into the garbage for disposal.

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Kids and Science: Experimenting with Ice, Salt and Colour

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You may have heard mention around here that it’s been an intense winter… and we’re still in it.  Last week we got into the spirit of ice and did a melting experiment at home inspired by this from Jean at the Artful Parent.  You probably have everything you need in your home:  ice chunks (made from bowls and mugs of various sizes), salt, and food colouring or watercolour paints.  You’ll also need a tray with a lip to contain the melted ice – baking trays worked well for us.  It’s nice to have droppers to add the dyes/paints, although you could also just slowly pour some of the liquid from a teaspoon.

It’s an easy and fun project that beautifully demonstrates the melting action of salt when it comes into contact with ice.  When sprinkled on, the salt crystals will bore holes and crevices into the ice upon contact.  Adding food dyes (which we used) or watercolour paints to the salted ice illuminates these miniature pathways with colour.  The results were striking.

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I think I can fairly say this is the most successful crafting project I’ve done with all three boys (7, 5 and 2) so far.  All three were completely engaged and, praise be!, my littlest could participate fully.  They love ice, just touching it, they enjoyed applying the salt, squeezing the drops of food dye from their little containers (each drop makes a dramatic difference), and using our own droppers to play around with the coloured water that pooled around the ice on the trays.

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They stayed at it for a good, long while.  Toward the end, I was hanging around the kitchen island watching them work and waiting for them to finish); they needed no assistance or input from me.  It was a bit messy, and their sleeves were wet (my two year old’s shirt was pretty wet too), but it was easy to clean up.  It was well worth it, and really quite pretty.

And Canadian winter that we’re in, this ice project will probably reflect the weather outdoors for a few weeks yet…

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