Printable Optical Illusions

Image of a 3D triangle optical illusion

We’ve created six printable pages of Optical Illusions for kids to encourage a curiosity in the world around them and how simple shapes and patterns can trick our senses. Not just great for stimulating discussion and observation, our simple optical illusions help children to improve their maths skills whether it’s for checking straight lines on the images or for measuring and comparing distances. They’ll find that their brain tells them one thing but the ruler says something entirely different … which do you trust ?!

As with any visual puzzles, each child will perceive the illusions uniquely. For some the illusion will literally ‘jump off the page’ whilst others may not be so easily tricked.

Preview of Circles in a Line Optical Illusion

Optical Illusion No.1

This optical illusion asks Are the circles in a straight line?

The wavy line helps to persuade our brains that the five circles are not in a straight line but the only way to be sure is to place a ruler or straight-edge on the page.

Preview of Crooked Line Optical Illusion

Optical Illusion No.2

Our second free printable optical illusion for children asks them Is the line from A to B straight?

When you glance at the two blue triangles and run your eyes along the line between A and B there definitely appears to be a slight kink or bend in the line … but as with the image above the only way to be sure is to lay a ruler on the sheet.

Preview of CIrcle Size Optical Illusion

Optical Illusion No.3

We ask Is the purple circle bigger than the green circle?

For some people the purple circle immediately seems to be bigger than the green one; others find it hard to spot any difference. Measure the diameter of the two to see if one is bigger than the other …. or whether they’re both the same.

Preview of Distances Optical Illusion

Optical Illusion No.4

Is the distance between points A and B less than the distance between C and D?

How’s your spatial awareness? The distance between points C and D certainly apears to be a lot bigger than the distance between A and B. Or is it just a trick of the mind? Print out this free optical illusion sheet and then carefully check the distances with a ruler.

Preview of Triangle Lines Optical Illusion

Optical Illusion No.5

Which black line is longer?

Most people soon figure out that both lines are the same length and that it is the slope of the triangle that makes the vertical line look longer. However this is a good example of how very simple shapes can easily trick our senses.

Preview of Which Side is Longer Optical Illusion

Optical Illusion No.6

Is side A longer than side B?

This final printable brain-puzzler is one of our favourites. An A4 page with two simple shapes and our eyes tell us that side A is definitely longer than side B … it must be ! …. measure them both and you’ll be surprised. Or maybe, by now, you’re not. We love optical illusions!