This fun and simple mini-experiment/craft uses household items to learn about some basic physics concepts and create a cool mini-hovercraft. This activity is intended for school-aged children and adolescents, though it can be fun for all ages, and helps them learn about air and form hypotheses about how the balloon mechanism works while serving as a fun activity that creates a cool “hovering” contraption! To add an artistic spin to it, decorate the CD base before gluing on the cap! Feel free to experiment with different cap and balloon types to see which styles work best.
Supplies:
Old CD
Hot glue gun and glue sticks
Party balloon (12” works best)
Water bottle cap (standard screw top or pull/disc/pop-top dispensing type with a small hole, old dish soap lids with a pop top work well!) *Multiple are shown in the image, but only one is needed for this activity*
Thumb tack (if using screw top cap)
*Markers for decoration optional, sharpie or similar style work best*
Instructions:
Step 1: The first thing you need to do before you start is get an adult to help with the hot glue steps and provide an extra pair of hands where it may be needed! Then, gather all listed supplies. If you are using a bottle lid with a dispensing hole, you do not need a thumb tack. Find a flat surface to use as your construction area. Have the adult helping you check to make sure that the glue gun is functional
Step 2: Now onto decorating the CD! This step is optional, but it makes your hovercraft more unique.
Create a design one one side of the disc using markers.
Let your creativity flow! It may be helpful to place a piece of paper under the disc to avoid getting any ink on the work surface.
Step 3: Next, set the water bottle cap on a flat surface and carefully poke about twelve holes in the top using the thumb tack. Set the tip of the tack where you want the hole to be and slowly push it in until it pokes all the way through. To avoid scratches, you can use a cutting board or other scratch resistant material as the flat surface.
*If using a pop/pull/press top lid with a dispensing opening, this step can be skipped*
Step 4: Now set the CD onto the flat surface, if you decorated it make sure the designed side is face-up. Place the bottle cap over the hole of the CD, try to make it as centered as possible. Then, have an adult helper use hot glue to seal the cap to the CD. A paper plate or towel can be used to catch excess glue that leaks from the glue gun. To make sure that the cap is sealed well, put a layer of glue all around the edge of the cap. Remember, this glue is hot, so keep your fingers away!
Step 5: Let the glue cool for at least ten minutes to make sure that it is secure and safe to touch.
Step 6: After the glue is dried, blow up the balloon and twist it closed, do not tie it! Using a hand to keep it twisted, pull the edges of the balloon opening over the bottle cap. It may be helpful to have one person hold the balloon and the other secure it to the cap using both hands.
Make sure to not let the balloon untwist!
Step 7: Now, set the hovercraft on a large flat surface like a table or the floor. Before you release the balloon, think about what you think will happen when you let go. How will it move? Will it move fast? Up and down or side to side? Now, let go of the balloon and let it untwist! Watch how it moves. Were your predictions right? Do you have any guesses as to why it works this way? If the balloon is falling too much to the side when released, use a cut cardboard tube or make a small paper ring to prop it up as it deflates and prevent it from tipping over. I cut a piece of paper and wrapped it around the balloon’s neck before securing it with tape to prevent mine from tipping.
Step 8 *Don’t read until after hypotheses are made*: The hovercraft should slowly move across the floor. It doesn’t fully float up, but the small force of the air escaping the balloon is just enough to create a small pocket of air between the hovercraft and the surface which allows it to glide across the surface. Once a balloon is used a couple times, it might start to get stretched out and not force the air out as quickly. If you notice your hovercraft isn’t gliding as well after a couple uses, swap out the balloon! The other components should not need any replacing. If a balloon is falling too much to the side, make a small paper ring to prop it up as it deflates and prevent it from tipping over. Make sure that the hole(s) in the cap are not too large or too small! If the hovercraft is not moving and the balloon is deflating slowly, try a cap with a larger hole or poke a couple extra holes in using the thumb tack. If you want to experiment more with this activity, try using different lids and balloon types to see which works best!