Introduction

 


Often misconceptions by students cause their learning to be skewed.  After doing some research, our group decided to investigate the misconceptions people have concerning shadows.  We assumed everyone had some prior knowledge of shadows and hoped to further investigate the topic by asking interview questions and revealing some of the common misconceptions.

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Research and Resources

 

Where do shadows come from?

Shadows result when light cannot pass through an object.  Since light travels in a straight line from its source, when it shines on an object, it does not bend to go around the source but instead is either absorbed or reflected by the object.  When we see a shadow what we’re actually seeing is a contrast between an area that has less light (the shadow) than the surrounding area. 

Researchers have found that children often have misconceptions about the source of shadows.  Robert Sweetland found that following misconceptions often occur with children:

 

Resources:

A“MAZE”ING SHADOWS: Teacher Page." MMSD Planetarium. 23 May 2003. Madison Metropolitan School District Planetarium. 27 June 2008 <http://www.madison.k12.wi.us/planetarium/amazing_shadows.pdf>.

Eschach, Haim. "Small-Group Interview-Based Discussions about Diffused Shadow." Journal of Science Education and Technology 12.3 (2003): 261-75. SpringerLink. Michigan State University. 27 June 2008 <http://www.springerlink.com.proxy2.cl.msu.edu:2047/content/q706077716h315k1/fulltext.pdf >.          

Implementing Conceptual Change Teaching in Primary Science, Daniel C. Neale, Deborah Smith, Virginia G. Johnson, The Elementary School Journal, Vol. 91, No. 2 (Nov., 1990), pp. 109-131. Publisher: The University of Chicago Press. <http://www.jstor.org/stable/1001746>.

Sweetland, Robert. "Light, Shadows, Rainbows Misconceptions." The HOB. 27 June 2008 <http://www.huntel.net/rsweetland/science/misconceptions/lightShadowRainb.html>.

 

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Questions

 

To determine various individuals' understanding of shadows, we interviewed 8 people, ranging in age from 2 to 29 years. We not only interviewed by asking questions but we also had them draw a picture of their own understanding of the concept of shadows.

The questions we asked were:

  1. Where do shadows come from?
  2. Do objects/things have shadows all the time?
  3. Do you have a shadow at night? How about in a dark room?
  4. Can you touch or step on your shadow?

*Often additional questions were prompted based on the responses of the interviewees.

We then asked them to draw a picture showing how a shadow works. We gave them markers/colored pencils and a piece of white computer paper and had them explain what they are drawing.

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The Video

 

 

 

Having trouble with the video above? Try this link to YouTube.

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Summary

 

The children we interviewed seemed to have similar misconceptions as those we found in the research.  We found that some children seemed to believe that shadows are attached to them and that some objects may not have shadows if they’re too big, as in the case of the little girl with the teddy bear example.  The younger children (ages 2-7) we interviewed were unable to give accurate, scientific reasons for where shadows come from, but instead said that shadows came from them or other objects.  The older child (age 10) and the adult we interviewed seemed to understand that shadows are a result of something blocking a light source, but only the adult was able to explain that light travels in a line and that a shadow comes from an object blocking the light’s path. 

When asked if objects had shadows all the time, several of the children said yes and then went on to explain specific objects that have shadows, but they did not explain why objects had shadows all the time.   However, when asked whether or not they had a shadow at night, all but one of the children said no, even those who said objects had shadows all the time.  They did not seem to be bothered by the contradiction, which fits with Jean Piaget’s Preoperational Stage in his theory of Cognitive Development.  Piaget found that children between the ages of 2-7 are able to have contradictions in their thought, which explains why some of the children we interviewed were able to say that objects have shadows all the time but they don’t have shadows at night.  Additionally, only one child and the adult were able to think outside of the box when asked if they could have a shadow at night.  The child originally said that she could not, but then referred to her prior knowledge of sitting near a campfire and seeing her shadow and concluded that she could in that context.  The adult also responded by saying that it depended on whether or not there was still a source of light available as to whether or not he could have a shadow.

Finally, the misconceptions that the students held were also showcased in their pictures.  For example, we know that having a light source is necessary in the formation of shadows.  However, only two of the interviewees included a light source in their pictures and only thought of the sun as being a valid light source.   Even when including the sun, only one child understood that the relationship between the placement of the sun, their body, and the shadow.  In addition, you’ll notice that the children would often draw their shadows as dark reflections of themselves.  These reflections would appear as separate objects and almost always appeared directly next to them instead of being a projection cast away from them. 

 

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"If you always face the sunshine, the shadows will always fall behind you." ~Walt Whitman

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