web addresses needed for optical illusions

[Ken Hawley <khawley@CAM.K12.IL.US>]

Hi folks....our second grade teachers are doing an online project with their
students that deals with optical illusions and how our eyes can trick our
brain.  Can anyone suggest some good web sites that deal with such a topic
and that "might" also be appropriate for this group?

Thanks in advance!!

Ken Hawley
Central A & M Middle School
khawley@cam.k12.il.us