Light and eyesight

4 eyes are better than 2!

 

Overview

This page reviews ideas learners use to explain light and being able to see. It includes misconceptions learners use to explain sight and research to support how difficult it is for learners to change their thinking.

Whenyoung learners are asked.

How does light help us see?

Very few of them answer with an accurate description:

Light travels from a source to an object and then to a person's eyes.

Their answer focus only on light falling on an object, objects, or anything in its path. And doesn't include the idea of light being reflected to our eyes. Examples the give include:

  1. Light shines on it so we can see.
  2. Light shines on things and brightens them so we can see.
  3. Light shines on all objects and anything else in its path.
  4. The eye sends out something (light, feelers, thoughts) to probe where we look to see.

Let's review the different categories fifth graders used to explain light and sight.

Categories fifth graders used to explain light and sight

Category One

Light travels from a source to an object and then to a person's eyes.

The diagram shows rays of light traveling from the Sun, source, to an object (tree) and then to the person's eyes.

Light reflects to eye

 

Category Two

Light brightens objects.

The diagram shows rays of light traveling from the Sun, source, and brightening an object (tree).

 

Category Three

Light brightens all objects and anything else in its path.

The diagram shows rays of light traveling from the Sun, source, and brightening all objects (tree, puddle, ... ).

 

Findings:

When learners were asked: How does light help us see? they found:

They read passages that included information about light bouncing and reflecting from an object to their eyes. Reading the text did not challenge 78% of the learners enough to change their misconceptions.

However, reading information such as: light travels in a straight line and light doesn't go through opaque objects, was understood by all students as they reported light travels in straight lines and to the objects we see. But it did not change their misconceptions about sight as they were somehow able to connect these ideas to their misconceptions without challenging their understandings. For example, when they learned the parts of the eye and how the eye works. They could have memorized that light enters the eye and traced it to the brain without thinking or asking, how the light got to the eye.

Consequently understanding how light reflects is essential for understanding sight and how the eye works, how we percieve color and what causes us to see color, what causes transparent; translucent; and opaque, and how lenses work.

Janet Eaton, Charles Anderson, and Edward Smith report three categories among the fifth graders they studied and how their understandings changed, or didn't change, after reading about how the eye and eye sight function. In their study of how
Student's Misconceptions Interfere with Learning: Case studies of fifth-grade students.

 

Related knowledge bases

 

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