Bill Badders, President of the National Science Teacher's Association, joined us to demonstrate some simple and exciting Halloween-inspired science experiments that parents can do at home, and to discuss ways parents can encourage their children to think about science in their everyday lives. After all, Halloween is the perfect time to get kids thinking about science! NSTA will be in town (October 24-26) for the first of three fall conferences which is expected to attract well over 2,500 science educators from Portland and across the country.
Ingredients• Corn Starch• Water• Food coloring
In a bowl, slowly add the water to the corn starch (you may want to color the water green...for added effect). Stop when the corn starch/water mixture is thick and gooey. Remember, you're making Oobleck...not gravy.
As your children explore the Oobleck, they should record their observations about the properties of the material:
• Can you pour Oobleck?
• What happens when you hold it in your hand?
• What happens if you poke it with your finger (quickly or slowly)?
• Can you roll it into a ball?
• Is it a solid or a liquid?
The Science Behind Oobleck
Is Oobleck a solid or a liquid? Maybe it is a solid and a liquid. Impossible. It can't be both. The truth...Oobleck is a non-Newtonian fluid. Most of the fluids we know are Newtonian fluids, but non-Newtonian fluids are a weird but interesting group of fluids. When a force (e.g. sqeezing, stirring, slapping) is applied to a non-Newtonian fluid, the viscosity (resistance to flow) of the fluid increases. In simple terms, any force you exert on a non-Newtonian fluid will make the fluid behave more like a solid. The more force you exert, the harder the fluid becomes. Strange but true! Other types of non-Newtonian fluids include quicksand, ketchup, and blood.
Static Powered Dancing Ghost
• A piece of tissue paper
• A balloon
• Black pen
• A head of hair
First cut out a ghost shape in the tissue as shown about 1.5 inches (4 cm) long and add some eyes with a marker. If you are using 2-ply tissues, peel apart the 2 layers to get the tissue as thin as possible. Cut out a few ghosts for more fun and place them on a flat surface. You might want to make some out of regular paper to compare. (Slightly heavier ghosts are sometimes easier to control.)
Blow up the balloon and tie it. Then rub it really fast through your hair for about 10 seconds. This will add a static charge.
Slowly bring the balloon near the ghost, and the ghost will begin to rise toward the balloon. (Our ghost “arms” actually reached toward the balloon as we got it near.) If the balloon is charged enough, the ghost will rise and float right up to the balloon, even when it is several inches away. With a little practice, you can get the ghost to rise, float, and even dance around. TIP: The easiest way to make the ghost rise without it sticking to the balloon is to tape the very tip of the bottom of the ghost to a table. The ghost will rise and move along with the balloon. With a good charge, the balloon can control the ghost from several inches away.
How’s it work?
When you rub the balloon through your hair, invisible electrons (with a negative charge) build up on the surface of the balloon. The electrons have the power to pull very light objects (with a positive charge) toward them – in this case, the tissue ghost!
The Screaming Quarter Experiment
• Dry Ice
• A Quarter
• Safety Goggles
How’s it work?
Dry ice is the solid form of carbon dioxide. As it sublimates, (turns back into a gas) the carbon dioxide gas escapes around the quarter causing the quarter to vibrate and make a rather spooky shrill along with occasional humorous sounds.