- Place a bicycle upside down and spin a wheel. Look at the spinning spokes through the slits in the Whirling Watcher. You can see the spokes stop, or move slowly forward and backward, like the wheels on a moving stagecoach in an old Western. In modern Westerns, special wheels with unevenly spaced spokes are put on the stagecoaches to avoid the strange appearance of backward rotation when the moving wheels are filmed. A regular set of wheels with evenly spaced spokes is used for scenes in which the stagecoach is not moving.
- Try making your own moving pictures. On the opposite side of the Whirling Watcher disk from the horses, in the space between each pair of slots, draw images, each of which is slightly different from its neighbors. (A running stick figure is an easy set of images to start with.) Look through one of the slots at a mirror, just as you did with the horses, and spin the disk.
Cow’s Eye Dissection
Learn about the different parts of an eye by watching a cow’s eye dissection at the Exploratorium.
“Seeing” Online Exhibits
Have fun testing your eyes and vision in these online exhibits and optical illusions from the Exploratorium “Seeing” exhibition.
Persistence of Vision
This activity from the Exploratorium includes an explanation of persistence of vision–-how your eye and brain “hold on” to a series of images to create a complete picture.
A Demonstration of Persistence of Vision
This engineering education site offers a pipe bottle activity that demonstrates persistence of vision.
National Museum of American History: Freeze Frame
Learn about Eadweard Muybridge, a brilliant photographer born in 1830, and see his famous photographs of animal and human movement.
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