We all have seen how children begin making sense of the world before they have any formal or informal teaching about a concept or topic…discovering through exploration that the world has textures, some things are for eating and some are not, objects can be moved and some appear to move by themselves, light comes and goes. A Private Universe (Harvard-Smithsonian Center for Astrophysics, 1987) is a now classic film revealing that early ideas that are not scientifically accurate, called misconceptions or incomplete ideas, may be held onto into adulthood. Recent college graduates are asked to explain why the moon seems to change shape and position. Why should we all be able to explain this natural phenomena? Not because it affects everyone’s daily life but because we should have had experiences that would allow us to use our reasoning to figure it out.
Understanding relationships between position of objects, and light and shadow, are necessary to understand how the appearance of the Moon’s phases occurs. We often learn about the Moon’s phases through reading and observing and moving a model of the Earth and Moon in middle and high school. By then we have had many experiences with moving objects and using light to cast shadows that change as the objects move. Learning about light through many different experiences helps young children build their understanding of how it works, learning about some of the properties of light. Part of being a child’s first teacher (after the family) is being aware of how beginning ideas may become misconceptions that children must discard before they can build a more scientifically accurate understanding.
One such misconception that some children believe is that all objects make light. Some objects (sun, flame, light bulb, lightening bug) do emit light. However, we see most objects by sensing the light reflected off their surfaces. The light originally comes from a source that emits light, such as the sun. Children may think that all objects emit light. Experience with trying to see an object in absolute darkness may be the experience they need to understand that only some objects emit light, such as light bulbs, flame and glow sticks, and that most objects do not create light.
In my effort to provide experiences for children that will help them build understanding of scientific concepts, I have to remind myself of a caution expressed by educator and researcher Jeff Winokur about teaching children. He said that, “Just because they see it doesn’t mean they understand it”. He was discussing teaching the difficult-to-teach concepts of water evaporation and condensation but I am applying it more broadly.
Setting up a situation where children can see light reflected from a surface such as smooth cardboard (but not a mirror), may broaden their understanding of reflection of light. Mirrored surfaces are not the only objects that reflect light. We see by sensing light reflected from any object we are seeing.
We must talk with our students, discuss all ideas and the evidence for holding these ideas. Ask children to consider alternative explanations for their observations and always encourage them to seek answers to questions. There is an on-going discussion about teaching to help students change their incomplete or inaccurate conceptions in a forum in the National Science Teachers Association’s Learning Center —look for “Avoiding Misconceptions in Science Education” thread in the “Elementary Science” forum.
In the October 2012 Science & Children I write about providing experiences where children can try using all of their senses to sense light, to help them build a beginning understanding of light and how it works. We built a “block out the light” box to view objects without light available. I think the children were disappointed not to see something amazing, but then they got it—with no light inside or coming into the box, they couldn’t see the object.
Read the Editor’s Note by Linda Froschauer, Hard to Learn Hard to Teach, for planning steps to support student learning. A Formative Assessment Probe–Talking about Shadows by Page Keeley, and a Science Short–Modeling Light and Shadows by David Carrejo and Judy Reinhartz also address the hard-to-teach concept of light.
Here are a few ways to use our senses to try to sense light. Add other ideas in a comment and please let me know if any of them are likely to lead to children making misconceptions about light!
|See||Have children identify all the sources of light they see during a school day (light fixtures, sun, flashlights, moon and other reflected light sources). Caution! Remind children never to look directly at the sun because it will damage their eyes even though they may not feel hurt.Looking at objects through various colored films (acetate) will give the experience needed to understand that the objects only appear to be a different color, they do not actually change color. When looking though a red film at an object children may say, ‘It’s red!” By asking, “Did it change color forever?” parents and teachers can prompt thinking about the properties of light and how our eyes sense light.|
|Hear||Have children close their eyes and listen for the “sound of light”. Have them listen to all available light sources to avoid thinking that a noisy fluorescent light fixture is the “sound of light”.|
|Smell||Use a flashlight with a quiet switch. Have children close their eyes and turn their backs to you. Have them tell you when the flashlight is on by sniffing for the “smell of light”. Have children sniff all available light sources to avoid thinking that a smell in the air is the “smell of light”.|
|Taste||From a safe distance, have children capture a mouthful of light from the sun, a light fixture or a flashlight and report on the taste, if any.|
|Feel||Use a flashlight with a quiet switch. Have children close their eyes and extend a hand in front of them. Have them tell you when the flashlight is shining on their hand by feeling the light. Many light sources make heat that we can feel but, in this activity, we focus on being able to sense light, not changes in temperature, with our skin.|