Draw a small dot on the left side of a piece of paper and an addition sign 6 inches to 8 inches away. Have a student close her right eye and look at the addition sign with her left eye. She should slowly bring the image closer to her face, while continuing to look at the addition sign. At some point, the circle disappears from her view, signaling that its image is now in the blind spot of her retina.
Have students cut two pieces of computer paper into pieces that are 2 inches wide and 3 inches long. They should draw on the right half of the pages. Each image should be a little bit different than the one before it, and they should tell some sort of story. They will then put the pages in order and staple them together. Flip the pages quickly to create what appears to be one moving image.
Give each student two coins that look exactly like one another. For example, give them each two quarters or two dimes. The students should hold their coins together in between their two index fingers. By rubbing the coins against one another in a rapid motion, the students will see an illusion of a third coin. Allow students to experiment with different-sized coins to see if the effect still comes out to be the same.
Give each student a piece of computer paper and have them roll the pages up into tubes. They should close one eye and look through the tube with the other eye at an object that is approximately 15 feet away. After 10 seconds, they put their other hand 5 inches away from the tube. Upon opening up their other eye and looking at this hand, they see what appears to be a hole in it.