# Oobleck

#### Kris Rosfjordand Elaine Cheong

Materials you will need:
• small paper bowls
• water
• food coloring
• cornstarch
• Ziploc bags

Introduction:

While one "instructor" is mixing up the oobleck, discuss solids and liquids with the students. First have them list as many solids and liquids as they can come up with, and write this list on the board. This then brings the class to the question:

How do you know if something is a liquid or a solid?

Procedure:

Have the students inspect the list of solids and liquids they created and come up with a list of adjectives to describe solids, and one to describe liquids. If they get stuck, questions to ask are:
1. Push Test -- can you push into it?
2. Pick-Up Test -- if you pick some up, does it all come up?
3. Pour Test -- does it pour out smoothly, or does it just fall out in a clump?
4. Shape Test -- does it keep the same shape?
Have the students copy down their list fo adjectives. Now you are ready for the oobleck. Distribute the oobleck in paper bowls. Have the students play with oobleck and make observations. Then, using the list of adjectices they created, have them individually decide whether oobleck is a solid or a liquid.
Once the students have decided whether oobleck is a solid or a liquid, gather them together and have a group discussion about their findings.

Note:

In a way, oobleck is both a solid and a liquid. It is a non-neutonian liquid. All that means is that it is a liquid that doesn't follow Newton's equations for liquids under pressure. A model for this is glass in very old buildings. This glass is thin at the top and thick at the bottom. That is because glass is also a non-neutonian fluid and is slowly flowing out of the the pane.

Reference: http://student.biology.arizona.edu/sciconn/oobleck/oobleck.html