Science SCI.IV.4.4 Grade: 7 Strand IV: Using Scientific Knowledge in Physical Science Standard 4: Waves and Vibrations – All students will explain shadows, color, and light phenomena. Benchmark 4: Describe ways in which light interacts with matter. Constructing and Reflecting: SCI.I.1.1 ­ Generate scientific questions about the world based on observation.
· Construct questions for each of the investigations suggested below to guide the design of the investigation. SCI.I.1.2 ­ Design and conduct scientific investigations.
· Experiment with mirrors to predict where a reflected beam will fall.
· Experiment with lenses to show how refraction is used to focus light. SCI.II.1.3 ­ Show how common themes of science, mathematics, and technology apply in real­world contexts. Vocabulary / Key Concepts
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reflection
refraction
absorption
transmission
scattering (or diffusion)
medium
lens Transmission of light:
· transparent
· translucent
· opaque Context Objects that reflect or absorb light, including mirrors Media that transmit light:
· clear and frosted glass
· clear and cloudy water
· clear and smoky air Objects that refract light:
· lenses
· prisms
· fiber optics Uses of lenses:
· eye
· cameras
· telescope
· microscope
· magnifying lens for magnification and light gathering
Knowledge and Skills Students will describe the many ways light interacts with matter. Light interacts with matter in many ways. Light can be reflected (bouncing off). This can be seen when a flashlight is shone on a mirror. It is through the reflection and absorption of light that we see objects and colors. Resources Coloma Resources: Sound & Light – Chapter 4, page 112 Looking at Images, page 122 (attached) Changing Colors, page 128 (attached) Other Resurces:
· Teachers’ Domain – Light – video clips, interactives, images and documents. Awesome!! (1 st link­ free sign­up, 2 nd ­ info)
Light can also be refracted (bending of light as it passes through a medium e.g. lenses, prisms, water, air). One can see this principle when trying to grab something in the water and it’s actually in a ·
different position than perceived. Finally, light can be transmitted (light passes through an object). If light passes straight through ·
a medium and the object can be seen clearly it is said to be transparent. If light is scattered as it passes through a medium and the object is distorted or hazy the medium is said to be translucent. If the light does not pass through the ·
medium and is absorbed and/or reflected, the object isn’t seen, the medium is said to be opaque. SMILE – IL Institute of Tech – Waves, Sound and Optics ­ single concept lessons vetted and posted by teachers. Excellent!
ThinkQuest – http://library.thinkquest.org/J0111285/The World of Light – outstanding site dedicated to teaching about light. Fun!
Physical Science Activity Manual –book written by a group of teachers using the learning cycle and 34 activities to teach physical science. Excellent resource!
Medium ­ matter through which light passes ·
The CSE Light Tour – excellent interactive learning!
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ExploreLearning – Waves, sound, and light – excellent site – free preview, but requires subscription.
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The Why Files – Why is the Sky Blue?
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Exploratorium – Glue Stick Sunset (why is the sky blue?)
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Exploratorium – Snacks about Light
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JCISD – Inquiry Activities for Light and Color EXCELLENT teacher materials – background info and masters!
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Michigan Teacher Network Resources
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Super Slinky, Laser Pointers
Resource Continued
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Science Explosion: Waves and Vibrations
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Bill Nye: Eyeball, Light/Color, Light/Optics, Sound, Waves Videoconferences Available For more information, see www.remc11.k12.mi.us/dl or call Janine Lim 471­7725x101 or email jlim@remc11.k12.mi.us IV.4.MS.4 Describe ways in which light interacts with matter 20/20 Science from COSI Toledo 7 th Grade Science Curriculum Technology Resources IV.4.MS.4 Vernier probes available: Light Sensor
Instruction Assessment Focus Question: What happens to light when it interacts with matter? “Make a light bend!” – lab (attached) As a class, students will discuss situations in the real world in which light is reflected (mirror/ calm water), refracted (light passing through water in a pool causing the perceived position of an object to be different from its actual position), and transmitted (stained glass window). Divide the class into groups. Give each group a flashlight. Groups must search the classroom and classify objects into categories: transparent; translucent; opaque; materials that refract, reflect, absorb, transmit, and scatter light. (Teacher may need to place some objects in the room to make this easier.) The teacher will explain the terms: transparent, translucent and opaque. Students will brainstorm examples of materials that have these characteristics. Students will make a shadow on a white surface using a very bright light in a dark room. Place transparent (overhead transparency), translucent (waxed paper), and opaque (construction paper) materials between the object and the surface. Have students observe the shadow on the surface in each instance. Discuss the differences in the outline of each shadow. Students will shine flashlights in a darkened room on a variety of transparent, translucent, and opaque objects (mirrors, plastic, clear water, water with a drop of milk, wood block, prism, etc.). With a partner, each student will classify objects into three categories based upon the way light does or does not pass through them. Students will use their knowledge of light and write a paragraph that explains a refracted image. (light passing through water in a pool causing the perceived position of an object to be different from its actual position.) Teacher Notes:
· Light travels in a straight line until it strikes an object. “To see an object, light from that object – emitted by it or scattered from it – must enter the eye. Light interacts with matter by transmission (including refraction), absorption, or scattering (including reflection).” (NSES) Transmission occurs when light moves through an object, which can be either transparent or translucent. Refraction occurs when light traveling through an object is bent into a new direction. Objects are magnified by microscopes, telescopes, etc. when light from the object is refracted and focused in lenses. Focus Questions
· How is light needed to see?
· What can happen to light when it strikes different objects, such as mirrors, glass, lenses, translucent materials, etc.? Notes The state benchmarks are very deliberately constructed to take students through these topics sequentially and developmentally. For example, students do not talk about sound and light as waves until the high school benchmarks – they only look at vibrating objects and mechanical waves such as those in slinkies or on water in middle school.
Skills Lab In this lab, you will control variables as you explore how images are formed by a convex lens. Problem How does the distance between an object and a convex lens affect the image formed? Materials per group tape convex cardboard stand light bulb and socket battery and wires lens blank sheet of paper clay, for holding the lens Analyze and Conclude 1. Is the image formed by a convex lens always down? If not, under what conditions is the meter stick image upright? 2. What happens to the size of the image as the Procedure: bulb moves toward the lens? What happens to 1. Tape the paper onto the cardboard stand. the position of the image? 2. Place a lit bulb more than 2 m from the paper. 3. What happens if the bulb is within one focal Use the lens to focus light from the bulb onto length of the lens? Explain. the paper. Measure the distance from the lens 4. Think About It. Make a list of the variables to the paper. This is the approximate focal this experiment. Which variables did you keep length of the lens you are using. constant? Which was the manipulated 3. Copy the data table into your notebook. variable? Which was the responding variable? 4. Now place the bulb more than twice the focal length away from the lens. Record the position and size of the focused image on the Design an Experiment With your teacher's approval and supervision, paper. Measure the height of the bulb. 5. Now, move the bulb so that it is just over one design an experiment to study images formed by convex lenses of various focal lengths. How does focal length away from the lens. Record the the focal length of the lens affect the position and position and size of the image. size of the images produced? DATA TABLE Focal Length of Lens ______ cm Distance from Bulb to Lens (cm) Height of Bulb: ______cm Image Position (upright or upside down) Image Size (height in cm)
REAL WORLD LAB – HOW IT WORKS Stage lighting in theaters uses color filters to control the colors of light on stage. In this lab you will study the effect of color filters on white light. Skills Focus observing, predicting, inferring Materials (per group) shoe box flashlight scissors removable tape red object (such as a ripe tomato) yellow object (such as a ripe lemon) blue object (such as blue construction paper) red, green, and blue cellophane, enough to cover the top of the shoe box Procedure 1. Carefully cut a large rectangular hole in the lid of the shoebox. The hole should be just a little smaller than the lid of the box. 2. Carefully cut a small, round hole In the center of one of the ends of the shoe box 3. Tape the red cellophane under the lid of the shoebox, covering the hole in the lid. 4. Place the objects In the box and put the lid on. 5. In a darkened room, shine the flashlight into the shoebox through the side hole. Note the apparent color of each object in the box. 6. Repeat Steps 3­5 using the other colors of cellophane. Analyze and Conclude 1. What did you see when you looked through the red cellophane? Explain why each object appeared as it did. 2. What did you see when you looked through the blue cellophane? Explain 3. What color of light does each piece of cellophane allow through? 4. Predict what you would see under each piece of cellophane if you put a white object in the box. Test your prediction. 5. Use diagrams to show how each color of cellophane affects the white light from the flashlight. 6. Think About It. Do color filters work more like pigments or like colors of light? What would happen if you shined a flashlight through both a red and a green filter? Explain. Getting Involved. Visit a local theater or talk to a lighting designer to find out how color filters are used to produce different stage effects.
LAB PREVIEW 1. Since both water and electricity are used in this activity, what precautions should you take? 2. What happens when light rays go through water? Can you recall seeing your reflection in the surface of a lake or other body of water? You can see your image because some of the light that reflects off your face also strikes the water's surface. However, you don't see a clear, color image because much of the light enters the water rather than being reflected. Would a person under the surface see a clear image of you? Materials light source. pencil clear rectangular container water notebook paper clay Procedure 1. Fill the container with water and place it on a sheet of notebook paper. 2. Outline the container on the paper. 3. Stand the pencil on end in the clay and place it on the paper in front of the container. 4. Place the light source in an upright position near the paper and turn it on. 5. Adjust the position of the paper and the pencil so the pencil's shadow on the paper goes completely through the container. 6. Draw lines on the shadow where it enters and leaves the container. Draw a line on the shadow that reflects from the surface of the container. 7. Move the container. Connect the lines to show the shadow through it.
NAME DATE CLASS Activity 19­2 (continued) Analyze 1. Draw a reference line (normal) at right angles to the container from the point where the shadow touches its surface. As the shadow enters the container, does it refract toward the reference line or away from it? What happens when the shadow leaves the other side of the container? 2. Experiment by changing the angle between the reference line and the shadow. What happens to the reflected and refracted shadows? Conclude and Apply 3. Compare the angles of reflection and refraction for light striking the flat surface of the container. 4. Would the angles of reflection or refraction change in Question 3 if the surface of the box were curved? Explain your answer.