Thursday, September 29, 2011

Light: Refraction: Flip an Arrow

This is a great way to kick off your study of refraction and lenses.

Provide students with a cylinder of water (without lines, words, etc. on it - check your recycling bin for empty glass bottles) and an index card with an arrow printed on it. 

Have the students observe the arrow, looking through the cylinder of water.  What happens as the move the arrow away from the water? 

How about when the move the arrow closer to the water. 

The cylinder of water is acting as a lens.  When the arrow is close to the lens, it is magnified, but pointing in the original direction.  As the arrow is moved away from the lens, it flips. 

Provide students with plenty of time to play with these simple objects, allowing them to make as many observations as possible.  Some ideas to try out:
  • watching the arrow through the water while the rotate the paper
  • holding the arrow vertically instead of horizontally
  • observing other shapes or letters through the lens
Once students have gained some hands-on experience with this simple lens, head back to the desks to work on explaining what was witnessed with words and diagrams. 

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