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K-1: The Senses

Author(s): Barbara Tharp, MS, Michael Vu, MS, Delinda Mock, BA, Christopher Burnett, BA, and Nancy Moreno, PhD.

Our Sense of Vision

Guiding Questions
Which parts of the body are involved in vision (seeing)? Is light important for vision? 

Concepts

  • All of the senses are connected to the brain. 
  • Our senses let us know what is going on inside and outside our bodies. 
  • The sense of vision (or sight) allows us to process information from light. 
  • Light is essential for vision. 
  • The brain processes information from the eyes, which are “light detectors.” 


Much of our understanding of the environment is made possible by our sense of vision. We are able to “see” because our eyes and brain transform signals produced by light energy into perceptions of movement, color and form. The capacity to recognize a face, identify an object under different light conditions, or interpret the components of a landscape is a product of complex processes that occur in numerous areas of the cerebrum (thinking part of the brain). Even our most sophisticated computers and software cannot duplicate the strategies used by the brain to enable our sense of vision.

We understand many aspects of how the visual system works. First, light enters the eye through the cornea, the transparent outer layer. The cornea bends (refracts) light rays that pass through the pupil (round hole in the center of the eye), and the iris (colored area that surrounds the pupil), opens and closes to regulate the amount of light that enters. After passing through the pupil, light is focused by the lens onto the retina, where it activates special light-sensitive cells, known as rods and cones. These cells convert light energy into electrical signals that travel along the optic nerve to the visual centers of the brain.

The primary visual cortex, where signals are first processed, is located at the back of the head. However, at least 20 additional areas of the cerebral cortex are devoted to processing visual information. Cells in different areas of the visual cortex respond to different characteristics of objects (for example, motion, form and color). This information is assembled along parallel routes, not yet fully understood, to form a three-dimensional mental perception of what is being viewed.

Note: Before class, use the template (see PDF) to cut out enough kaleidoscopes for all students. Prepare each kaleidoscope for folding by scoring the fold lines (dotted lines) with a ballpoint pen and straight edge. This will facilitate accurate folding. If students are not capable, fold the kaleidoscopes in advance, but let students refold and tape them together during the lesson. Make a small hole in the sheet of construction paper (see Part 2, item 7 in the PDF).


Procedure: Part 1

Have students sit in a circle. Place an apple, orange or other colorful item in the center of the circle. Ask students to share observations about the item. Make sure they mention the color. Ask, how do you know the color of the object and how are you able to describe so many details? Students should mention “vision,” “eyes” or “seeing” as being essential for describing the object.

Have all students close their eyes. Turn the lights off and darken the room as much as possible. Tell students to open their eyes and observe the object once again. Ask, Does it look the same? If not, how is it different? Students should notice that with limited light, the color is not as bright. Depending on the level of darkness attainable, the object may even be barely visible. Explain to students that light is necessary for vision (“seeing”), and the object’s appearance has changed because less light is available.

Explain that they are going to make kaleidoscopes, which will enable them to see new combinations of shapes and colors. Give each student a cut out template for the kaleidoscope. Demonstrate how to make the folds, and help students tape the flap over the top edge.

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