Stereograms are pictures that look like random patterns until your eyes focus on them in a particular way, allowing you to see an image.  If you can focus your eyes so that your right and left eye are looking at separate parts of the image, your brain is tricked into putting it together and forming a 3-D picture.

Below are some stereograms for you to have fun with.
We'd like to thank www.net1plus.com/users/darias for allowing us to use these images.  Many more can be found at that site.

To see the hidden pictures, bring your eyes close to the screen, then slowly pull your head away.  Pretend that you're looking at something behind the image.  You can also try crossing your eyes, but the pictures will appear backwards and are much more difficult to see that way.
 
 
 
 
 

#1 - bird landing
 
 
 
 
 
 
 

#2 - two deer and tree
 
 
 
 
 
 
 

#3 - skull
 
 
 
 
 
 
 

#4 - triceratops