Oobleck Lesson Plan
Background
Scientists have attempted to explain the unusual properties of Oobleck and similar substances in various ways. There is extensive literature on the subject including a 1906 article by Albert
Einstein.
When most fluids cool they become more viscous. This means that their resistance to flowing increases. Cooking oil is a common example. Such fluids are called Newtonian. But there is another class of liquids called non-Newtonian. Their viscosity increases not with temperature, but when the liquid is stirred or compressed. But naming the property doesn’t explain it, and some scientists have concentrated on the shape of starch molecules and how they fit together.
Others have speculated that the electrical charge of the molecules is the key to Oobleck’s strange behavior.
If you decide to discuss this question with your students, begin by asking them for their ideas on why Oobleck behaves the way it does. Then ask them to imagine that they can see the individual molecules of cornstarch and water and to think about how they might act when being poured or pushed and pulled. This gives the students the opportunity to formulate their own models.
In one possible model, the starch molecules are compared to sand and water in a plastic squeeze bottle. The grains of sand are closely packed with a little water in between. The water’s surface tension doesn’t allow all the space between the sand grains to be filled with sand. Squeezing the bottle gently forces the sand grains to move against each other. This increases the spaces and allows more water to fill the spaces. The more gently you squeeze the more time there is for the water to fill the spaces and provide lubrication. But if you squeeze the bottle quickly, there isn’t enough water between the sand grains and friction between the sand grains resists the flow.
Although sand grains are much larger than molecules of starch, starch molecules are quite large and the mix of cornstarch and water may react very much like a mixture of sand and water. This is one explanation for why Oobleck flows like a fluid, but reacts as a solid when suddenly compressed.
Other scientists base their Oobleck models on chemistry. Cornstarch is made of long chain molecules called polymers. When water is added to cornstarch and the mixture is compressed, the molecules become "tangled" and are unable to slide easily against one another.
A third model suggests that starch molecules acquire an electric charge as they rub together. The faster they are rubbed, the more electrical attraction is created among the molecules. This causes the increase in viscosity.
You could end the discussion by explaining just how difficult it is to observe what’s going on at a molecular level just by observing the properties of a substance. Since there is no conclusive explanation of why Oobleck behaves as it does, suggest to your students that perhaps one day

one of them will become a scientist and discover an explanation for the strange properties of
Oobleck that everyone will agree is the correct one.
Materials
 Large mixing bowl
 Many boxes of cornstarch
 Measuring cup
 Water
Making Oobleck :
Combine the cornstarch and water in a mixing bowl. The first step is to form student groups to investigate Oobleck. Emphasize that Oobleck is safe to handle, but standard safety procedures still apply. Students are not to taste Oobleck, get it in their eyes or horseplay during the activity.
They must also wash their hands after the activity. Assure the students that Oobleck will not stain clothing.
Tell the students that their job is investigate the properties of Oobleck. They will be expected to record their observations and share them with the class. If they are unclear on the concept of property (aspects of a substance that we can sense or that can be detected by instruments that extend our senses use a piece of chalk or other familiar object and have the students quickly identify some of its properties.
Give each group a container of Oobleck and allow them to begin their explorations. After several minutes, give them a large sheet of paper and markers so they can record their observations.
When the students are nearly done, tell them to finish their list of properties and have each group share its results.
Extensions
Have your students think about what Oobleck might be made of. You can assign this as homework and have the results shared with the class the next day.
Send each student home with a small sample of Oobleck in a plastic bag or other air tight, unbreakable container. Remind them to keep it in the refrigerator when they aren’t using it. Ask your students to introduce Oobleck to their friends or family, and to notice how their family and friends react to this strange substance. Have your students share their experiences with the class.
References http://education.jlab.org/beamsactivity/6thgrade/oobleck/index.html