This is perhaps the easiest “machine” to make in the book and is a dramatic demonstration of the effect of soap on water.

EXTRAS: written instructions and the science of how the soapy surfer works can be found in this piece I wrote for BBC Focus Magazine.

Click here for an article on why washing your hands with soap is better for killing viruses than using just water or alcohol-based wipes or handwashes.

Below is a video I made with the Royal Institution in which the comedian Rufus Hound shows his son how to use this phenomenon for a rather splendid “magic” trick:

MORE GOOD STUFF: Click here for more activities. I’ll be publishing more videos of activities from my book over the coming weeks. Check back here, follow me on Twitter or subscribe to my YouTube channel to make sure you don’t miss them.