Physics of Light Activities
Before conducting any of the following experiments with the students, be sure to run some practices to ensure that the lighting in the room works to achieve the desired outcome.
Students will consider and discuss the following questions: What is light? What happens The students will any responses on chart paper or the board to refer back to as the unit progresses.
Share with the students that scientists who study light admit that they don't know everything there is to know about light. But whatever light is, we're very lucky that it exists:
light is what enables the human eye to see.
Scientists do know how light reacts under certain conditions. Three reactions of light are demonstrated in the following science experiments. These experiments can be done in one session or over a couple of lesson times. Space and distribution of materials can be challenging. These experiments should be conducted with groups of 3-4, with each student having the opportunity to perform the activity. Preparing 4-6 sets of materials is helpful making setup, cleanup and transition easier.
Experiment #1: Light Reflection – Make a Disappearing Penny Reappear
Items needed: pennies, bowls, water
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Place a penny in the center of a small opaque (you can't see through it) shallow bowl.
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Set the bowl on a table in the classroom
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Group members take turns keeping an eye on the penny as they slowly backs away from the bowl.
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Tell your friend to stop as soon as the edge of the bowl just blocks his view of the penny.
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Now tell him you will magically make the penny reappear.
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Slowly fill the bowl with water without disturbing the penny.
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Does your friend see the penny come back into view?
Observation: After a sufficient amount of water is added to the bowl, your friend says he can see the penny.
Explanation: As water fills the bowl, the reflection of the penny bends around the bowl to the surface of the water, making your friend think that he can see the penny again.
Experiment #2: Light Refraction – Make a Simple Magnifying Glass
Items needed: jars or drinking glasses, cereal boxes
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Place a clear round jar or drinking glass close to the ingredients list on a cereal box. (This choice of reading material might inspire the students to practice this at home.)
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Look through the jar at the printing.
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Are the words easy to read?
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Now fill the jar with water and place it close to the ingredients list again.
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Are the words easier to read?
Observation: When the jar contains water, the printing on the cereal box appears much larger.
Explanation: As light enters the curved jar, its course is altered or bent by the water. This bending, or refraction of the light, results in your homemade magnifying glass.
Light Diffusion – Make a Simple Light Projector
Items needed: construction paper in five colors, five round items to use as patterns, pencil, scissors, glue stick, shoeboxes with lids, ruler, one flashlight per group
Teacher preparation:
Measure, draw and cut a one-inch square in the center of each small end of each shoebox. This would be a good project for a volunteering parent to help with.
Student Preparation:
Students in their groups will cut five circles from different colors of construction paper in the following diameters: 3 inch, 5 inch, 7 inch, 9 inch, 11 inch. Provide round items or templates for patterns. The students will glue the circles in a target format with the 3-inch circle onto 5-inch circle, the 5-inch onto the 7-inch, the 7-inch onto the 9-inch, and the 9-inch to the 11-inch.
Place the lid on the shoebox.
Experiment:
Dim the lights in the classroom where the experiments will take place.
One group member holds the construction-paper target up
Another group member holds the shoebox about one foot away from the target.
A third group member shines the flashlight through the holes in the shoebox so the light falls directly on the center of the target.
Gradually move the target away from the shoebox.
What happens to the light as the target is moved?
Observation: As the light source becomes farther away from the target, the light spreads over more of the target's surface and its brightness becomes dimmer.
Explanation: The beam of light is strongest and brightest inside the shoebox. Once it passes out of the box, the light begins to spread out in straight lines to fill the larger area. Some of the light rays reflect or bounce off the paper target and scatter around the room. This scattering of light is called diffusion.
Follow Up:
Read
The Magic School Bus Gets a Bright Idea: A Book About Light
to the class. In this story, Ms. Frizzle's class thinks the PTA light show is pretty wild, but really surprising things happen when the show is over. Ms. Frizzle and the Magic School Bus arrive just in time to help solve the mystery and teach about the properties of light. She starts the story explaining to the students that "there is no sight without light." This is a helpful transition text for students to begin learning about the biology of the eye.
Biology of the Eye Activities
Activity #1:
The Eyes Have It: The Secrets of Eyes and Seeing
Students will listen to the read-aloud and generate a word bank in their science journals as well as on chart paper or bulletin board area. The introductory text blends photos and cartoon-style art to explain the fun facts and serious science about the human eyes as well as the visual systems of other creatures.
Activity #2: Students will use the glasses cardboard template (similar in size to 3-D glasses) to identify parts of the human eye.
Items Needed: cardboard templates of glasses, colored pencils, science journals
Procedures:
Using colored pencils, students will draw and label the parts of the eye on the front (lens) part of the glasses, including iris, pupil, sclera, upper lid, lower lid.
Students will then label the sides of the cardboard glasses with the internal parts of the eye, including retina, macula, vitreous fluid and optic nerve. An enrichment component could include identifying the rods and cones in a cross-section of the retina.
Art Connection Activity
Activity: Color vs. Black and White
Luminance is measured light reflecting off a surface. Brightness is perceived luminance, therefore luminance is objective and brightness is subjective. This activity will help to demonstrate the difference between the two.
Items needed: images on pages 112-137 in
Vision and Art: The Biology of Seeing
or several prints of paintings, black and white copies of the same paintings, crayons, markers, chart paper for vocabulary
Vocabulary to introduce: three dimensional, shading, luminance, depth
As a exploratory activity, students will create colorful illustrations using crayons or markers. Once the pictures are done, photocopy them in black and white. Students will make comparisons about the two versions of their work.
After creating their own images, students will be introduced to a variety of colorful paintings and/or prints. Class-wide discussion of colors and objects in each print will help the students "read" the painting and discover information about it - what do you notice, where do your eyes go, what might be happening are all prompts for conversation and vocabulary. After viewing the images, students will see the same image in black and white and discuss the questions and prompts. What used to stand out and now is less obvious? What other changes do you see?
Individual Culminating Activity
Kaleidoscope from a Potato Chip Can
Almost everyone has looked through a kaleidoscope (from a Greek phrase meaning "to view a beautiful form"), a popular toy invented by Sir David Brewster in 1816. This activity will bring the work of the eye and physics of light together in a fun, useful activity.
Making a Simple Kaleidoscope
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Items needed for each student:
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regular size can of Pringles Potato Chips
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cardboard from a cereal box
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aluminum foil
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scratch paper/newspaper
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tape
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nail or knitting needle
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clear acetate
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translucent, plastic gemstones, buttons, glitter
Procedures:
1. Turn the can upside down. Use the scissors (or a large knitting needle or nail) to puncture an eyehole about 6 mm in diameter inward in the center of the metal end.
2. Decorate the outside of the can.
3. Cover 3 strips of 22 cm x 6.25 cm cardboard strips cut from the cereal boxes with aluminum foil.
4. Tape the foil-covered strips into a equilateral triangle prism. Use several pieces of tape to hold the configuration in place.
5. Fit the triangular prism into the can.
6. Cut a circle from the stiff clear acetate precisely the size of the can opening.
7. Lay the circular shape on top of the triangular prism.
8. Line the inside of the can between the acetate circle and the top rim of the can with a cardboard spacer strip, joining the ends with a small piece of tape.
9. Fill the upper compartment about half full with the acrylic gemstones or other translucent items, then put on the plastic lid.
10. Hold the kaleidoscope up to the light, look into the eyehole, and
Slowly rotate the can. The three mirrors will reflect the objects under the lid and produce the kaleidoscope effect.
