Optical Illusions in Geometry

So it was a regular day in Geometry class and everyone had finished their test so we decided to chill in the back of the room.  Richard got bored so he brought out his little book of optical illusions.  In a matter of 10 seconds every boy is huddled around Richard freaking out of the illusions in the book.  One illusion told us to stare at the page from 30 seconds and we all stood perfectly still and everyone was laughing at us.  After about 10 minutes of getting our mines blown we class was over.  I will put some of the illusions down below.