Incidental Blog #9 The Science of Magic


What’s the difference between Magic and Science? Not much! In fact all magic tricks are based on scientific principles. Scientists aren’t very good at keeping secrets though - the processes of what they’ve done are often just as important as the answers they discover!


Here are a few magic tricks that we can explain to kids with some basic science;


Illusions –

The human brain is very complicated and clever, but it can also be tricked quite easily! An illusion is an image which fools our brains into thinking one thing, instead of another thing. Magicians often use distractions (like waving their hands about) to make us focus on that one thing, whilst they trick us by doing another.


Here is a great example of an illusion that you can show your kids. Your brain will understand and process it is a picture of a duck, until you turn it to the side and then you will see a rabbit. Once you’ve seen both animals, you can only focus on one at a time. It will always look like either a rabbit or a duck, but not both – it’s an illusion that has confused your brain!


Colour Magic –

The physics of colour is surprisingly quite a large topic to cover. However, starting with the basics is a great idea, even with older children – you may be surprised at what they do and don’t know. Here is an experiment that you can do easily at home:


Colour Mixing



4 glasses or plastic cups

Red, blue and yellow food colouring





This is a very simple but effective way for kids to learn the very basics of colour chemistry. Begin by explaining that there are three main colours, called primary colours, which create all of the colours we can see. When we mix 2 primary colours together, we create a compound colour.


  1. Fill the cups with water.
  2. Add a few drops of each colour to three of the cups, leaving the last one transparent.
  3. Ask your child what each of the colours are called
  4. Then ask them what colour will be created if we mix the blue cup with some yellow food colouring and then either add a few drops to see whether their hypothesis is correct or incorrect.
  5. Repeat with all the cups, stirring and adding a few more drops of colour into each cup to display the different types of compound colours there are. If the child is old enough, let them add the colour or stir, so it becomes an interactive lesson.
  6. Once you get to the last cup you can show them what happens when you add three primary colours together. You will always get brown (good to know when you’re painting a picture!).


Invisible Ink –

Chemistry is full of surprises and always a great way for kids to explore basic ideas with hands-on activities. Invisible inks have been used for hundreds of years, with people using sweat and even spit to write secret messages to each other. There are many types of invisible ink but a great one to use at home uses milk and heat.


Invisible Milk Message



A small cup of milk

A paintbrush or cotton-bud

A piece of paper

An iron

An ironing board or towel and flat space



Milk ink effectively weakens parts of the paper, those parts are then quicker to burn than the paper itself and so the message in ink turns brown and the rest of the paper remains white. The milk message will dry almost completely invisible until you burn it with the iron to reveal the secrets!


  1. Take your paintbrush or cotton bud and dip it into the milk.
  2. Write a message or draw a picture onto your paper.
  3. Wait for the paper to dry – the message should be invisible.
  4. Then turn your iron on, making sure you’ve turned it to dry mode – we don’t want any steam.
  5. Once it is hot enough, place the piece of paper message side down on the ironing board or towel, and place the iron on the paper for about 10 seconds.
  6. You’ll begin to smell the milk burning, you can check the bottom of the paper to see if it has browned enough. If not then place the iron back down on the paper for another 10 seconds.
  7. Be careful not to heat the paper for too long, as you’ll ignite the paper.
  8. Always make sure you supervise any use of irons around children, they can take awhile to cool after turning them off so make sure they’re out of reach.
  9. Your secret message will be revealed and will cool very quickly.


Geni McCallum is the Marketing Manager and Community Educator for Science Alive! She lives in Christchurch with her partner, step-daughter and cat. 

The opinions expressed in this article are those of the author, and do not necessarily reflect the views of Science Alive!