This balloon and CD hovercraft will educate your teens about how things fly 

Is your adolescent a fan of science fiction films? If that's the case, they've probably seen a lot of cool spaceships that hover and float around like magic. Yes, there are crafts that hover about both on land and water. These are called hovercrafts. They float on a cushion of inflated air. Although it may appear to be magic, it operates on the basis of pure science. Here is an easy-peasy experiment to explain the science behind the functioning of a hovercraft. 

What you’ll need   

• Pop-top lid from a plastic drinking bottle. (Reusable plastic drinking bottles sometimes use these kinds of lids). 
• An old CD or DVD  
• A medium-sized balloon  
• Craft glue or super glue 

• Stopwatch or timer 
• Large flat surface for testing the hovercraft 

How-to 

Get these on a table, call your kid and start the activity. Here’s a step-by-step guide for the process: 

• Remove a pop-top lid from a plastic drinking bottle. 

• Glue the pop-top lid's base to the CD or DVD so that the lid covers the CD's hole in the centre. Allow for thorough drying of the adhesive. 
• Ensure that the pop-top lid is securely closed. 
• Fill the balloon with as much air as you can without it popping. Then compress the neck to prevent any air from escaping. 
• Stretch the balloon's neck over the pop-top lid without allowing any air to escape. Make sure the balloon's opening is centred over the pop-top lid's opening. Your hovercraft is now equipped to do hovering manoeuvres. 
• Set the hovercraft down on a level surface. Start your stopwatch or timer, pop the lid open, and push the hovercraft. When the hovercraft stops hovering, stop the stopwatch. 

• Remove the pop-top lid from the balloon. 
• Repeat the process two more times, this time expanding the balloon up as much as you can safely, securing it to the pop-top lid, and monitoring how long the hovercraft stays in the air. 
• Rep the process three times more, but only blow the balloon up to a medium size this time. For example, if it took three breaths to inflate up the balloon as large as you could safely, it should only take two breaths or a bit less now. 
• Continue the process three times more, but just blow the balloon up to a tiny size this time. For example, if it took three breaths to inflate up the balloon as large as you could safely, only use one breath or less now.  

What is happening in this experiment? 
The air from the balloon passed under the hovercraft thanks, to the pop-top lid. This means that even if we tested balloons of various sizes, the opening that allowed air to flow beneath the hovercraft was always the same size since the pop-top lid remained the same. The balloon held the most air when it was inflated to its maximum size, which should have allowed the hovercraft to hover for the longest time. Similarly, when the balloon was inflated to its smallest size, it held the least quantity of air, therefore the hovercraft should have hovered for the shortest duration, and when the balloon was expanded to a medium size, it should have hovered for an intermediate amount of time.