Reprinted from Connect
Vol.11 No.4, March/April, 1998
Focus on: Matter
Grade Level: K-8

Mystery Matter

by Charles James

The author, has helped many students to explore matter through his development of informal physical science programs in Washington, DC. In these three "recipes", he encourages exploration of materials that behave in unusual ways.
The matter in these investigations raises a variety of questions, some of which Charles James suggests below. Many more ideas will come from your students. But the only way to uncover their ideas is to let them experiment. — Editor.

Here is a unique opportunity for students to compare three unique substances commonly known as Glurch, Oobleck and Slime. Using the following recipes, students can try their own variations of each recipe and record their results.

Divide the class into small working groups of four to five students each. Allow 10 – l5 minutes for each group to "manufacture" a sample of each mystery material. This can be done at a central mixing table or individually at each group’s workplace. In the first round of experimentation, have students follow the recipes carefully, since comparison of the three substances by the whole class is the initial objective. This first phase should take at least 45 minutes to allow plenty of time for each group to complete a series of tests on their materials.

Group consensus on the outcome of each experiment should be obtained before recording their results. A compilation of the entire class results can be made at the end of the 45 minute period or used as the initial step. Try not to inhibit the "messing around" that will naturally be a part of this activity.

Simply prepare for the mess in advance and have the students help in cleaning up the room at the end of the exploration.

Recipes for materials

Plastic cottage cheese/margarine containers can serve as mixing bowls and, if necessary, storage containers over a two/three-day period. All of these materials will dry out over time with exposure to air.

I. Glurch

• 1/2 cup of liquid laundry starch or high quality laundry detergent
• 1/4 cup of white glue
• 1/2 teaspoon of salt

Mix the laundry starch and salt first, then add glue, stirring continually. Once a lump of material forms (making it difficult to stir), squeeze remaining liquid in the trash or a separate "waste sludge" container. The rubbery material that remains is your Glurch.

II. Oobleck

• 1/2 cup of dry cornstarch
• 1/4 cup water

Add water slowly to the cornstarch, mixing with fingers until all the powder is wet. It may take a little less or a little more than 1/4 cup of water to get the right consistency. The material should be liquid enough to drip slowly from your fingers, yet feel solid when pressed on the surface (in your container).

III. Slime*

• 1/2 cup polyvinyl alcohol or guar gum
• 3 tablespoons sodium borate solution

Add all three tablespoons of sodium borate at once to the alcohol, stirring constantly with another spoon or your finger. Once material thickens, stir a little longer, until you can get a thick gelatin-like material which can be removed from your container and handled.

Questions

• Which substance holds its shape the best?

• Which substance bounces the best?

• Which substance leaves a mark on your hand?

• Which substance stretches the farthest?

• Which substance flows faster when cooled?

• Which substance changes the most over a period of time?

IMPORTANT NOTE: When you are done with these mixture(s), place in a plastic bag or jar and dispose in the trash. Do not pour the mixture down your drain; it will clog the pipes.

*Materials for this activity can be purchased through Flinn Scientific, Inc., 131 Flinn St., Batavia, Illinois 60510. Call 800-452-1261.