Upside-down water glass trick is an awesome STEM kids science experiment for kindergartners and preschoolers to explore air pressure and gravity.
Is it possible to fill a glass with water and turn it upside down without spilling? This Upside-Down Water Glass Trick will leave your preschooler in awe! Besides, you will be using commonly available items, so no specialized equipment is required. Most importantly, this STEM kids science experiment will reveal how air pressure and gravity work in a fun and hands-on way!
WHAT you will need for this Upside-Down Water Glass Trick:
- paint samples (you can also use index or playing cards, or a thick cardstock)
- various cups
- science glasses (buy blue here and pink here)
HOW to conduct this STEM Kids Science Experiment:
Before you get started with your Upside-Down Water Glass Trick, make sure your paper is large enough to completely cover the mouth of the glass. First, pour water into the glass, filling it to the top. Next, cover the mouth of the cup with the paper. Thereafter, while keeping your hand on the card, turn the cup upside down. Lastly, slowly take your hand away and the paper will stay in place, as well as the water. The trick works as long as the paper doesn’t become completely soaked. Make sure to hold the cup over the tub or waterproof tray just in case of an accidental spill.
Ways to adapt Upside-Down Water Glass Trick:
Try this experiment by changing the amount of water in the cup. Also, try different containers. Does it make any difference? Will a wider cup hold the paper better than a narrower cup? Does the temperature of the water have any effect on the water staying inside the cup?
Revealing the Science Mystery behind this cool STEM Trick:
The mystery is the air that we breathe! Air molecules in the atmosphere exert almost 15 pounds of pressure per square inch of surface area. However, we do not notice it because our body is used to feeling this kind of air pressure. When you turn the cup upside down, the pressure of the air inside the cup and the air pressure outside the cup is equal. So, you might notice that a little water leaks out between the paper and the cup. The leak happens because the force of gravity pulls down on the water. When some of the water escapes, this causes the volume of air (the space above the water inside the cup) to slightly increase. Even though the amount of air above the water stays the same, the volume occupied by the air is now greater so the air pressure inside the cup decreases. So, the pressure of the air outside the cup is now greater than the pressure inside the cup. Also, the water creates an airtight seal between the rim of the cup and the paper, thus keeping the paper in place. However, when the seal is broken even slightly, air enters into the cup, equalizes the pressure, and the gravity pushes the water out. When the pressure of the air molecules inside and outside the cup is the same, gravity takes over, and the paper falls down, spilling all the water!
Please, always supervise your children.