THE MIXTURE CAN CLOG DRAINS. PLEASE DISPOSE
OF CAREFULLY. [Let the mixture settle, then pour off the water.
Scoop the remaining semi-solid material into a plastic bag and place
in regular trash.]
Questions to Ask
How does the (dry) cornstarch feel?
Have you ever felt anything like this before? What was it?
How do you think it will feel if we spray the dry starch with water?
What happens when you squeeze it? How does it feel?
Can you make anything with this? What happens as you try?
Tips for Less Mess
Cover the table with newspaper or a plastic tablecloth. Have paper towels and a garbage bag handy. Old clothes, smocks, and aprons would be appropriate.
The cornstarch and water stirred together create a mixture. When the solid grains of cornstarch are evenly spaced apart in the water, the starch grains slide easily past one another, as liquids do. When the mixture is squeezed, the grains are pushed together. This pressure makes the starch molecules stick together in a different way, so the mixture acts like a solid. When the pressure stops, the molecules come unstuck again, returning the mixture to liquid form.
** This mixture may be refrigerated in a closed container for continued use. **
To be a chemist and create a mixture called a suspension.
What You Need 1 box of cornstarch
Spray bottles, straws, eyedroppers, teaspoons
Container for mixing
What to Do
Have children pour cornstarch in the container. Encourage them
to feel the dry cornstarch grains. Using a fun tool such as a
spray bottle or dropper, add water-- feeling the consistency of
the mixture as it changes.
Chemist: A person who studies elements and the compounds they form. Chemists often mix compounds together creating new substances with different physical properties.
Cornstarch: A natural nutrient carbohydrate found in the stem, root, and fruit of a corn plant.
Mixture: A solid or liquid dispersed in a liquid or gas.
Suspension: Tiny particles of a solid dispersed, but not dissolved, in the surrounding medium.
Add more cornstarch or water and see what happens to the mixture. When you are able to gather up a handful of the mixture, squeeze it firmly. What happens? Now if you stop squeezing and hold it quietly in your hand it will ooze through your fingers. Add several drops of food coloring to the surface of the mixture. Take a toothpick and drag it through the colored drops. What happens?
Ask the children what else they would like to mix with water. Look in the kitchen for ideas.