Learning new things is fun, and when you add Phil of Science into the mix the Hub Lab makes it even more craic.
Here, he is using marshmallows and balloons in the experiment, so you have a ready-made excuse to buy some!  

We want to do two things in this video...
1.  Understand the effects of pressure 
2.  Use mechanical devices to use air pressure to change the volume of materials

Mmmm Marshmallows are just fluffy wonderful puffs of delight. There really isn't very much to them, they're just sugar and air. You use them to demonstrate how pressure and volume and inversely proportional to each other.

Whaaaa?? That means when the value of one goes up the value of the other goes does. So if you increase the pressure on something is should get smaller. It also means that the volume goes up the pressure goes down. Imagine a balloon going deeper under water. At about ten metres below the surface it’ll be half the size it was originally.


This is the easiest experimental procedure we have. The difficulty is not eating the marshmallows before you're done!

  • Put the marshmallows into the bottle and fill them up to at least ¾ the way up the side. Use sweets that will just fit inside the next of the bottle but don’t cut of tear the marshmallows as they will stick to the side.
  • Attach the air pump to the top of the bottle and start adding air.
  • This will increase pressure and you should see the marshmallows decrease in size.
  • When you’re ready, slowly release the pressure and allow for the air to
  • come out. The marshmallows with regain their original size.

You can download the full guide to running this experiment here!

This one will be really enjoyable for everyone! And you can watch it again any time on RTÉ Player

Phil and all the After School Hub crew want to see your own experiments: Upload your content here