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Comparing how light moves when it reflects and refracts. |
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FIRST GRADE – REFLECTION AND REFRACTION
OBJECTIVES:
VOCABULARY:
MATERIALS:
BACKGROUND:
Physics helps us explain the world around us. There are many things
occurring in the world that we can't explain. This unit has students
investigating the properties of light. They will not understand the
physics of light, but will begin the process of becoming familiar with
some of the bizarre things light can and cannot do.
The world is full of images for children. A reflection in a mirror or
window can scare them; a penny in a pool may look closer than it really
is. Light has always played with our sense of sight. Children can learn
how these images are different from the real thing. Children need to
discover that they can change the way light moves. As children play with
optic toys, they begin to see that light can play tricks with their eyes.
Light can be controlled by lenses, prisms, and mirrors. Light moves.
Lenses are important in our everyday life. Many people wake up putting on
eyeglasses or contacts. People who take pictures use lenses in the
cameras. Lenses are in magnifiers, lighthouses, microscopes, telescopes,
binoculars and projectors. Nature has found a natural way to create a lens
system in most organisms (eyes) so they can see. The word lens comes from
the Latin word "lentil," (a bean used in soup that is biconvex.)
A prism causes light to change direction or refract as it
moves through the prism. Light when it travels through different
substances can also refract. It appears to our eyes as if the object is
bending, but it is only "light" playing tricks with our eyes. A mirror
allows light to "bounce" or reflect from the surface
of the mirror. We see ourselves in the mirror because light reflects or
bounces from the mirror and the image is captured by lenses in our
eyes. Light can also diffract when it goes through a small
slit. The light particles spread from the center into distinct
packages. Depending on your
class we usually do not expect the students to learn this term, but saying
the term is allowed.
Many people do not realize that light is actually a real phenomenon. It
moves, it changes directions, and it is part of a branch of physics called
the electromagnetic wave spectrum.
PROCEDURE:
In this lab, students will "play" with light. Students will view several
examples of reflection and refraction and will try to discover how light
moves.
1.
Use slideshow and go over how light can move.
Go over the parts of the eye and emphasize the shape of the lens the lens and how the lens
makes the image upside down.
2.
Give students a biconvex lens and an index card (white).
Have them focus an image onto the paper.
They will see that the
image is upside down. To do
this, the best way is to turn out the lights and have light come in from
the windows. Can also use the
slide projector image
3.
Skip to
slide10—refracting bends light and reflection bounces light. Go over objects that reflect and refract. Common objects include mirrors
(reflect); glass of water with spoon in it (refract); foil (reflect); oil
in a glass bottle (refract); prism (refract); glass (refract); lens
(refract); or any shiny surface (reflect).
4.
Give each student a mirror in pairs.
Have them play with reflection by working with a partner and put
the two mirrors opposite and see if children can see infinity reflect.
Make sure they put something in the center.
After they see infinity,
you can also have them hold the mirror horizontally at eye level so that
the students either see the ceiling or the floor. They can tilt the mirror
back and forth so it looks like people are walking on the ceiling.
They usually get very excited doing this.
5.
Then give students a bag of quartz, ulexite, and calcite.
Tell them these all refract light but refract it in different ways.
Have them discuss how the mineral refracts the line. (quartz can
make multiple images, ulexite will bring the picture to the top (color
image is better), calcite will make it double).
Students can also put the mineral to their eyes and look at
objects. The calcite will
double and the quartz will make rainbows; the ulexite does not have an
image because the individual crystals are small fibers.
Ulexite has boron
within its structure which only allows light to go one direction.
Boron is an ingredient used in making fiber optics.
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Young
children need to experience different examples of reflect and refract to
recognize them easily. Reflect is easier to understand than refract.
Reflection is just a "bouncing" back of an image, while refraction is a
change of direction of an image. A prism, for example refracts or bends
light to create a rainbow. However, with just a little guidance, students
can look at light and identify whether it refracts or reflects