When I am looking for science explorations to do with the kids, I have to take into account two very different levels of skill and understanding. Lily is almost 7 and Ethan is only 3 and a bit.
Until recently, Lily and I tended to do experiments while Ethan was napping but he is increasingly capable and interested in joining in and I am keen to encourage that.
To facilitate this, I have been looking for fairly simple projects or ideas that Lily can manage mostly on her own while I help Ethan. This hovercraft is just the thing to do with kids of a variety of ages. I recently also used it in a workshop with 15 kids aged from 5 to 10-years-old – It was a huge hit, especially as I gave everyone time to custom paint and decorate their hovercraft.
- A CD (If you don’t have one lying around, Kmart and Office Works have them).
- A balloon.
- Glue that will adhere to metal and plastic*
- A pop top from a drink bottle**
- Permanent markers and jewels or decorative objects.
- A straw.
*Note: Bunnings has a range of glues and you will be able to find one there. I have also used a low temp hot glue gun but found that the glue does not fix well to the metal on the CD.
**Note: If you don’t have a pop top but have a normal bottle lid from a soft drink or water bottle you can use a metal skewer or nail to put a hole in that. It will work but is just harder to operate as you can’t shut the air flow down.
Paper or a journal and a pencil for making notes and illustrations.
- If you are going to decorate the CD, do that first.
- Glue the pop top so that it fully covers the hole in the CD and wait until the glue is fully dry.
- Inflate the balloon as fully as possible.
- Place the opening of the balloon over the pop top or lid so that it is secure and won’t fly off when the air is released.
- Place the hovercraft on a flat smooth surface. Polished floor boards, desks, kitchen benches and dining tables are all good options for this.
- If using a pop top, open the valve and watch the hovercraft float.
If you make more than one hovercraft you might want to set up a racecourse and use straws to blow the hovercraft along. Building on that idea, you could set up an obstacle course and time each person as they blow the hovercraft around. Just remember that you only have a short time before the balloon deflates so don’t be too ambitious with the length of the course.
The hovercraft works because the force created by the air leaving the balloon through the hole in the CD is greater than the force of the gravity that was originally holding the CD on the flat surface you placed it on.
The result is that a cushion of air forms between the surface and the CD. There is less friction between the CD and the air than there was between the flat surface and the CD and this allows the CD to glide when it is blown.
There are things that we take for granted that our kids don’t necessarily know. Here are some ideas to tease out the science in this activity.
- Once you have put your hovercraft together but before you release the air from the balloon, ask your child what they think will happen (they are forming a hypothesis).
- If you are using a pop top, close off the air supply and get the child to try to blow the hovercraft with the straw. Then, open the air supply and try again. Ask your child to think about and try to explain why the hovercraft moves when the air is flowing but not when the pop top is sealed (change in test conditions).
- Run a bath and test whether the hovercraft works on water (change in test conditions).
- Get younger children to draw a picture of what they have done. Older children might be interested in adding labels with explanations about what has been happening.
How did you go? What things did you discover? We would love to hear your stories in the comments below or to see your pictures on Instagram or our Facebook page.
If your kids enjoyed this, they'll love our hot air balloon experiment! And if they just can't get enough of science experiments then grab our Chemistry-in-Action kit and keep them occupied and learning for days on end!