Fish in a Bowl
This activity discusses Optics/Perception and teaches about the persistence of vision.
What You Need
- Glue or stapler
- Paper strip
- Pencil or marker
- Straw
Guide:
Safety Notes
Ensure you are familiar with Let's Talk Science's precautions with respect to safe virtual outreach to youth.
What To Do
- Cut paper into a strip approximately 1/3 the size lengthwise of a 8 ½" x 11" sheet of paper.
- Fold paper in half so it forms a card.
- On one side, draw a picture of a fish on the other side, draw a picture of a bowl decoration can be added.
- Place straw in the middle of the card so it looks like a popsicle stick not like a flag.
- Glue or staple in place.
- Hold the straw between the palms of your hand and move back and forth rapidly so that the straw spins and watch the card.
Discovery
When the straw is rotated rapidly the fish appears to be inside the bowl. Whenever we see an image, the brain holds onto that image for a short time 1/16 of a second. If another image appears within that time then we will see both images. This is called PERSISTENCE OF VISION. Movies and cartoons depend on this phenomena. If approximately 24 slightly different pictures move in front of the eye each second, they will blend together to make a moving picture.
Other pictures to draw could be:
- Bird in a cage
- Pumpkin with a face for Halloween
Let them try other pictures too!
What's Happening?
When the straw is rotated rapidly the fish appears to be inside the bowl. Whenever we see an image, the brain holds onto that image for a short time 1/16 of a second. If another image appears within that time then we will see both images. This is called PERSISTENCE OF VISION. Movies and cartoons depend on this phenomena. If approximately 24 slightly different pictures move in front of the eye each second, they will blend together to make a moving picture.
Investigate Further
Other pictures to draw could be:
- Bird in a cage
- Pumpkin with a face for Halloween
Let them try other pictures too!