Oobleck!

To conclude our Solids and Liquids unit in science, we asked, "Is oobleck a solid or a liquid?"  For those of you unfamiliar with oobleck, it is a gooey substance featured in Dr. Seuss' Bartholomew and the Oobleck.  In the book, oobleck is made on Mountain Neeka Tave by some mischievous magicians to appease an ungrateful king.  While the magicians used ingredients such as mouse whiskers, ours is much simpler.  I have posted the detailed recipe, minus the mouse whiskers, below.

Students were asked to test the oobleck for properties of solids and properties of liquids, and record their observations on a worksheet.  We found that oobleck sometimes acted hard like a solid, but was other times fluid and viscous like a liquid.  We also found that it was sometimes dry, and other times wet.  What a mysterious substance!  After some debate, we thought...could it be both?  Well, scientifically it cannot be both, but this Non-Newtonian fluid does behave as both.  Therefore, whether a student concluded it was a solid or a liquid, there is no wrong answer!  The object was just to get them to think about it.

Oobleck Recipe

Ingredients:

·     Two teaspoons of cornstarch

·     Water

·     Food coloring (optional)

Directions:

1.  Put about 2 heaping teaspoons of cornstarch into a cup.

2. Add about 2 teaspoons of water into the cup.

3. Mix ingredients together.  You know it worked if it is difficult to mix, but there are no chunks of dry cornstarch.  You should be able to poke it without getting your finger wet.  You should also be able to roll it into a ball and see it melt back into your hand.

4. If it is still too runny, add more pinches of cornstarch until it is a gooey consistency.   

5. If it is too dry and chunky, add a few more drops of water.

6. To color your oobleck, add a few drops of food coloring.