# VIDEO: Back to School Science - Experiments to try with kids after school

Published: Aug. 31, 2021 at 7:44 AM EDT

GREENVILLE, N.C. (WITN) - School is back in session, but the learning doesn’t have to stop in the classroom.

Ms. Covey Denton popped by the WITN News at Sunrise studio Tuesday morning to demonstrate some science experiments that you can recreate at home.

Be sure to watch the attached videos!

Descriptions from Ms. Denton:

Soda Can in Coffee Mug

In weather, you hear a lot about high and low pressures. Bernoulli’s principle says that in areas where air moves rapidly, the pressure is low. This principle explains how an airplane can fly (due to the shape of the wing) and how a pitcher can throw a curveball (due to the spin of the ball) and how two years ago, I was able to cover the studio in toilet paper!

When you blow across the top of the cup and the can, you are lowering the air pressure. This drops the pressure so the higher air pressure of the surrounding air pushes the can up and out of the coffee mug. You can also move things horizontally by blowing between two cups suspended on a string. The area of low pressure that is generated causes the surrounding air to push the two cups together. In the studio, we are moving small items, like cups and soda cans, but in weather, these pressures can help to move giant air masses through our atmosphere!

Tea Bag Rockets

This should only be done under adult supervision!

These rockets lift off similar to hot air balloons. So what is the science behind what is happening?

As the teabag cylinder burns, the air that is inside is heated. When the air gets heated, the molecules move quickly and spread out, making it less dense (density is just how much stuff is packed into a specific space). This means that the air inside the cylinder is less dense than the air outside. Just like with weather systems, warmer, less dense air rises above cooler, denser air. The difference in these air densities causes a convection current-- the hot air rises and the cooler air outside the burning cylinder moves in from the bottom to fill the space it is leaving behind. Once the teabag burns, the light ash frame is all that is left. Because it is so light, the force of the hot air rising is strong enough to lift it upward. As it cools, it falls back down.

Convection currents like these are easily observed at the beach with refreshing sea breezes during the summer. During the day, the sea is cooler than the land, so the air above land is heated and rises, causing the cooler air from the sea to rush in. That’s why during summer days, the breeze is almost always blowing in off the water.

Heavy Air

This should only be done under adult supervision!

Heavy air?? Most of us don’t think about air having a weight, but that is exactly what we are measuring when we talk about the air pressure. We all know that some gases are less “heavy” than air (less dense)-- helium for example allows our balloons to float. Did you know that there are gases that are heavier than air (more dense)?

In order for a fire to stay lit it needs oxygen, fuel, and heat. Firemen call this the “fire triangle.” If you take away any one of the three, the fire will go out.

When you mix baking soda (sodium bicarbonate) with vinegar (acetic acid), you are mixing a base with a weak acid. This creates a chemical reaction with the final end products being water and carbon dioxide (CO2). All of the bubbles you see when we mix them are made of CO2! This reaction produced so much CO2 gas that it pushed the other gasses up and out of the container. Since CO2 is denser than air, the container is filled with it. Even though it is invisible, you can pour the gas just like a liquid. As you tilt the container, the CO2 gas pours onto the flame. That means that air can’t get to the flame and it goes out because of the lack of oxygen.

Some commercial fire extinguishers use CO2 to extinguish the flames.

Covey Denton is an award-winning science teacher in Wilson, NC. She and her kids make regular appearances on WITN News at Sunrise.