by Mark Cohen
completed in partial fulfillment of the requirements for
"Teaching High School Physics"
PHY 301
Autumn 1997
Illinois State University
|Carl J. Wenning, Instructor
A. Optics is one of the fundamental topics in the study of physics. This unit will present optics to a student in their first physics course. Subtopics in optics include the fundamentals of light: illumination, color, reflection and refraction with mirrors and lenses, diffraction, and interference. The intended students are in their first year of high school physics. The unit will be taught using an inquiry as well as thematic approach. Students are required to have one year of high school algebra as a prerequisite. The text used will be Merrill's Physics.
B. Students studying this unit of optics will learn a variety of content, process skills, and dispositions. The content included in optics is fundamental to a students' comprehension of the operation of some everyday devices, such as cameras, and the observation of phenomena associated with light. Process skills learned by the student will include oral and written communication skills and the ability to use the scientific method, in congruence with the Illinois Learning Standards. Finally, dispositions elicited in this unit will include skepticism when encountering data and curiosity about the universe.
C. It is important that all students have a understanding of optics. Any individual who has ever taken a picture with a camera or listened to a compact disc has used some of the applications of optics principles. The same applies for an individual who watches television or wears glasses. Students will also grow more scientifically literate as a result of their study of optics, which would tend to make them more successful in the future. In addition, advances in our ability to manipulate light through the application of the principles of optics have benefited our society tremendously, giving us new ways of communicating, treating disease, and creating art. As a society we have benefited from the photograph, by understanding light's effects on matter. Advances in laser technology allow us to treat cancer through a greater understanding of interference and light intensity. Finally, art forms such as movies are completely based on our ability to recreate and manipulate light using lenses and images. Because our society uses principles of optics in its function, the individuals in society would benefit from a background knowledge of optics, as well as the gain in scientific literacy. The scientist and professional also requires an understanding of how optics can be applied in their fields. A chemist must know if his reagents will decompose or react if exposed to light at certain intensities or frequencies. An engineer must also know and use optical theories when designing, for example, the heads-up display used in aircraft and automobiles. Finally, a professional jeweler must understand how reflection and refraction influence the look and ultimately the selling price of a gemstone.
A.
Unit Topic Concepts Time
I. Kinematics distance, displacement, speed, velocity, acceleration 2 wks
II. Dynamics forces, vectors, projectile motion, periodic motion 2 wks
III. Momentum impulse, change in momentum, conservation of 2 wks
momentum, elastic and inelastic collisions
IV. Energy potential energy, kinetic energy, conservation of 2 wks
energy, work, power, simple machines
V. Circular Motion rotational velocity, centripetal and centrifugal force, 2 wks
moment of inertia, angular momentum, conservation
of angular momentum
VI. Universal Gravitation Galileo, Brahe, Kepler's laws, Newton's law of 2 wks
universal gravitation, Cavendish, motion of planets
and satellites, weightlessness
VII. States of Matter thermal energy, heat, changes of state, laws of 2 wks
thermodynamics, gases, pressure, fluids, solids
VIII. Waves transverse and longitudinal waves, properties of 2 wks
waves, superposition of waves, standing waves,
diffraction and interference
IX. Sound sound waves, speed of sound, frequency, amplitude, 2 wks
Doppler effect, resonance, sound quality
X. Optics properties of light, speed of light, light sources, 5 wks
light and matter, color and the spectrum, reflection,
refraction, mirrors, lenses, optical instruments,
diffraction, interference
XI. Electricity electric charge, conductors and insulators, electric 5 wks
force, Coulomb's law, electric field, electric
potential, current, resistance, circuit diagrams,
Ohm's law, electric power, Kirchoff's law, series
parallel circuits
XII. Magnetism magnetic fields, magnetic force, electromagnetism, 3 wks
currents in magnetic fields, Faraday's law, motors, generators, Lenz' law, transformers,
electromagnetic waves
XIII. Modern Physics blackbody radiation, photoelectric effect, Compton 5 wks
effect, wavelengths of particles, atomic structure,
lasers, radioactivity, fission, fusion, relativity
B.
Parts of the curriculum in physics are not in units or textbooks. Some parts of this "hidden" curriculum include dispositions toward science as well as scientific literacy. Physics teachers have the entire academic year to influence their students to be more curious and scientifically literate through their expectations, as well as the types of activities presented. Physics teachers that initiate open-ended and student directed activities as common practice will develop students with the ability to use the scientific method and make sound judgments about situations and information. Using inquiry lessons to elicit student activity and curiosity results in deep learning instead of memorization. In addition, ethics and communication are also developed among students working in cooperative activities with other students. These skills and dispositions are not taught at any one time, but must be reinforced in daily activity throughout a year long curriculum.
A. The basic properties of light
1. How we see things
2. Definition- range of frequencies in electromagnetic spectrum
3. Light travels in a straight line in MOST cases
4. A ray (particle) or a wave?
B. Measuring the speed of light
1. Roemer's method
2. Michelson's method- Nobel Prize
3. The International Council of Weights and Measures definition
C. Sources of light and illuminance
1. Defining a luminous body vs. an illuminated body
2. Luminous flux (rate at which light is emitted)- units in lumens, candela
3. Illumination on a surface- units in lux
4. Illumination decreases as distance from source increases- 1/radius^2
D. Light and Matter- Bohr Model
1. Transparent
2. Translucent
3. Opaque
E. Color and the spectrum
1. Energy and wavelength in relation to color
2. Primary colors
F. Refraction
1. Snell's Law
2. Index of refraction
3. Speed of light in a medium
4. Total internal reflection and critical angle
5. Dispersion of light
6. Effects of refractiona. fiber optics
b. mirages
c. sunsets
G. Reflection
1. Diffuse vs. specular reflection
2. Mirrorsa. virtual images
b. concave mirrors
c. focal length
d. spherical and parabolic mirrors
e. real and virtual images with concave mirrors
f. convex mirrors
g. spherical aberration
H. Lenses
1. What is a lens?
2. Pinhole lenses
3. Concave and convex lenses
4. Real images from convex lenses
5. Virtual images from convex lenses
6. Virtual images from convex lenses
7. Thin lens equation
8. Optical instrumentsa. The eye
b. Corrective lenses
c. Magnifying glasses
d. Microscopes
e. Telescopes
f. Cameras
I. Diffraction
1. Discovery- Grimaldi
2. Definition- Huygens
3. Single slit diffraction- sound vs. light
4. Resolving power of a lens
J. Interference
1. Constructive and destructive interference of waves
2. Young's double-slit experiment
3. Diffraction gratings
4. Lasers
A. This unit of optics has as its goal the learning of some major content objectives. Some of the content knowledge to be acquired by students is this unit includes:
1. Light is a small range of frequencies in a greater electromagnetic spectrum.
2. Light has an approximate finite speed of 300,000,000 m/s.
3. An object that emits light is luminous; an object that reflects light is illuminated.
4. State the difference between transparent, translucent, and opaque.
5. Explain that objects have color because they reflect and absorb specific frequencies of light.
6. Explain the concept of index of refraction and its relation to the speed of light in a medium.
7. State Snell's law.
8. Explain the definition of focal point, virtual image, real image.
9. Explain the formation of real and virtual images using convex and concave lenses.
10. State the definition of diffraction.
11. Explain how light waves interfere, and what interference patterns look like.
12. State and apply the thin lens formula.
13. State and apply the interference formula.
B. In addition to the knowledge acquired through this unit of optics, students will also demonstrate the following skills:
1. Solve problems involving the speed of light in various mediums.
2. Solve illumination problems.
3. Use Snell's Law to determine angles of incidence or refraction, or the index of refraction of a particular material.
4. Use the mirror equation to calculate the location and magnification of images with convex and concave mirrors.
5. Use the thin lens equation to calculate the size and location of an image with a convex or concave lens.
6. Use derived equations to relate pattern width and slit width to the wavelength of light in single slit interference problems.
7. Use derived equations to relate the distance between slits, the distance between the slits and the screen, the distance between two adjacent bright bands of light, and the wavelength of the light involved in double slit interference problems.
C. Students will have certain major scientific dispositions when entering the physics classroom. This unit is designed with the goal of changing the dispositions of the students, making them more scientifically literate individuals. Some ways to affect these changes include:
1. By using an inquiry approach to lessons rather than a lecture approach the students will spend more of their time thinking actively about the topics in the unit. This has the effect of transforming the learning experience from a type of surface learning to a more deep understanding of the material.
2. Optics is a subject that can be observed readily in the world around us. Therefore, a hands-on type of learning experience where the students 'learn by doing' promotes their critical thinking skills, process skills, and sense of discovery. These are all important in the development of scientific literacy.
3. Most students in the physics classroom use equations having little idea of their physical meaning. By providing exercises which seek an explanation or a theory rather than a value or quantity, this unit will reinforce the students' ability to evaluate a system and derive an equation or law, not vice versa.
A. (See attachment)
B. Many students do not recognize the fact that each point on a light source is radiating light in all directions. This is because textbooks show selected rays from sources and students are never asked to, "sketch diagrams in which they themselves show the multiplicity of rays emerging from each point on the object" (Arons, p. 221) Students also hold misconceptions about the images seen in plane mirrors. Twenty to thirty percent of students in a preinstruction survey thought that images in plane mirrors were formed on the surface, instead of behind the mirror (Arons, p. 222). This shows a deficit in the ability to conceptualize rays of light and their paths correctly. Next, students hold many alternative conceptions about the formation of images with converging lenses. A large number of students, "fail(ed) to recognize the absolute necessity of (a) lens for image formation." (Arons, p. 223) When covering half of a lens, the majority of postinstruction students stated that half of the image would disappear. This is a result of the fact that their preconception blocked their ability to learn the concept. (Arons, p. 224) Finally, students have problems understanding how they see. "The act of seeing is not explicitly associated with the arrival of light at the eye of the observer." (Arons, p. 226)
Two learning styles which I have observed have profound effects in students' retention of content are deep and surface learning. Deep learning involves a student focusing on significant issues in a particular topic. The students will relate their own previous knowledge to new knowledge, theoretical ideas, and evidence. Surface learning takes place when students focus on key words or memorization, and do not distinguish principles well.
The deep approach to learning works much better for long term comprehension. This is because the concept is understood instead of memorized. Students get the feel for the principles and concepts, not the facts and the answers. A deep learner has a better organization of ideas, and is able to recall them and apply them more easily. A surface learner covers so many facts by memorization that it becomes difficult to see underlying relationships.
Procedures which some teachers perform on a regular basis promote primarily surface learning. These techniques seem to help students, but they help students score well on tests, not learn content. These techniques and procedures include providing study guides, using multiple choice tests, "teaching to the test," and having low expectations for achievement. These things encourage rote memorization and do not promote a thorough understanding of the concepts.
Some ways that teachers may encourage deep learning include open-ended assessment tools, stating high expectations, having clear explanations of interesting topics, and teaching for depth. Open ended assessments such as essay questions, projects, or alternative assessments make students organize information. This organization helps their own learning. High expectations means that students are always challenged and thinking. They cannot be passive and "get by." When an interesting topic is presented, students are usually actively listening. By providing clear explanations, students can better relate the information to their previous knowledge. Finally, teaching for depth does not mean detailing students into oblivion. It is the process where a teacher looks to see that the students can structure the concepts and know what meaning the concepts have. Though equations are very important to the study of physics, they are only a means to the end of an understanding of physics. Because of this, students (and teachers) should focus on the themes and concepts over the memorization of equations.
A. (See attachment)
B. Chapter 9 of Arnold Arons' book A Guide to Introductory Physics Teaching (1990) applies to my unit of optics, but only in part. I will therefore refer to the sections which deal with the concept of optics.
9.11 Sketching Wave Fronts and Rays in Two Dimensions
Most textbooks have excellent diagrams of the transmission, reflection, and refraction of light waves. In addition, there are some great demonstrations that can be performed in class, as well as videotaped demonstrations using lasers and ripple tanks to show how wave fronts and rays behave at boundaries of material. However, students are very rarely given the chance to exercise their knowledge of this concept because there are very few homework or test questions which require them to sketch wave front or ray phenomena. Students should be asked to sketch the incident, transmitted, and reflected rays, as well as indicate changes in wavelength and velocity with the wave fronts. This phenomenon can be learned without the mathematics, and is mastered with a little practice. Practice is the most important part of the learning, not matter how clear the demonstration.
9.15 Young's Elucidation of the Dark Center in Newton's Rings
Thomas Young shed light on the wave/particle nature of light debate with his modification of Newton's rings experiment. At the time it was not understood that a light wave inverted in phase as it was reflected. By analyzing mechanical systems such as waves in strings, he devised an experiment where light passed through three mediums of increasing index of refraction. The light reflected, if inverted in phase, would cause a bright center instead of the dark center in Newton's experiment (with two pieces of glass separated by air). The fact that the dark center could be explained by destructive interference and that the bright center could be explained by phase inversion and constructive interference led great credit to the wave theory of light. This experiment provides the student an opportunity to solidify their knowledge of wave reflections as well as follow the process of scientific reasoning in a historical experiment.
9.16 Specular Versus Diffuse Reflection
Students have many preconceptions in this area of optics which are difficult to correct. Even after instruction students fail to correctly conceptualize the way in which objects are illuminated. "Probably the most significant gap that develops in this connection is the failure of students to become explicitly conscious of the fact that all nonself-luminous objects that we see are seen by diffuse reflection of ambient light and that each point on the object acts as a point source, reflecting light in all directions." (Arons, p. 221)
The failure to see light as traveling in all directions from each point carries over to luminous sources as well. The poor performance in this area is attributed to students' lack of homework and test problems dealing with this topic. "Assigned problems tend to concentrate on numerical or geometrical determination of image positions with mirrors and lenses, and students are rarely impelled to visualize the overall array of physical phenomena" (Arons, p. 221)
9.17 Images and Image Formation: Plane Mirrors
Goldberg and McDermott (1986) conducted a study about student conceptions of images in plane mirrors. Students were surveyed before and after instruction. Three tasks were asked of the students. The first task required students to locate the image they saw in a plane mirror. Most students understood that the image was behind the mirror after instruction. The second task asked students to determine whether or not the image would move if they moved to the left of the mirror 2 feet. Half of the students responded incorrectly initially, though after instruction and drawing ray diagrams many students responded correctly. The third task asked of the students required them to guess if they would see an image, and if the interviewer would see an image (from a different position). Those who answered incorrectly used two different kinds of reasoning to conclude if they or the interviewer would see the image.
9.18 Images and Image Formation: Thin Converging Lenses
Goldberg and McDermott (1987) again tested students on their ability to conceptualize images. In this investigation, students were working with an optical bench and thin converging lenses to form images of the filament of a light bulb. In the first task about half of students (both pre- and post-instruction) failed to recognize that no image of the bulb would form on the screen without a lens. "Even though they (students) are fully aware that images of everyday objects in the room do not form on the walls, they do not invoke such everyday experience when viewing the optical bench." When students were asked to predict what would happen if half of the lens were covered, almost all predicted half of the image would vanish. This number lessened slightly after instruction. Next, about half of the students failed to recognize that if the screen was moved that the image would become fuzzy. Students seemed to have difficulty with the concept of focal length. Finally, the majority of students both pre- and post-instruction did not recognize that they could see the image without the screen by positioning themselves about two meters beyond the initial screen position.
9.19 Novice Conceptions Regarding the Nature of Light
Students have many preconceptions regarding the way light arrives at our eyes from illuminated objects. Reflection in general is not viewed properly when associated with light reflected off of objects to the eyes of an observer. In addition, color filters on lights are seen as adding color to white light, rather than transmitting only part of the white light. It is noted that "Rapid assertions of the 'correct' view do little good." (Arons, p. 226)
9.20 Phenomenological Questions and Problems
When teaching optics, "One very powerful type of question is the 'What will happen if?" variety that cultivates hypothetico-deductive reasoning." (Arons, p. 226) It is also recommended that teachers ask students to sketch effects for changes in various aspects of a particular problem. "Such changes are rarely demonstrated in connection with discussion of pattern formed by thin films, and even if demonstrated, the ideas do not register unless students are asked to sketch the effects for themselves." (Arons, p. 227) The main idea here is that students need practice with phenomenon in order to comprehend them.
C. Three lesson plans are to follow. They are: (1) Concept Change/ Constructivist, (2) Inquiry-based Learning, and (3) Cooperative Learning.
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AUTHOR: Cohen, Mark DATE: Dec. 10, 1997
COURSE NAME: Physics GRADE LEVEL: 11-12
UNIT TITLE: Optics CONCEPT: White Light
OBJECTIVE: The student will discover that white light is made up of all of the colors of the spectrum, and that the we see colors on objects because all other wavelengths of light are absorbed.
CONTENT:
I. White light is made up of different colors.
A. Prisms separate white light into a spectrum.
B. Rainbows act like prisms.
C. By mixing the primary colors of light you can make white light.
D. When white light is separated into colors by traveling through a medium it is called dispersion.
II. Light is dispersed when traveling through media because of the difference in index of refraction for different colors.
A. Different wavelengths of light travel at different speeds.
B. Difference in the speed of light causes a difference in the index of refraction.
C. Materials with high indices of refraction accentuate great dispersion of light. Ex.- Diamonds.
III. Light that we see from illuminated objects is diffusely reflected from an ambient source.
A. White light strikes all of the surfaces.
B. Dyes selectively absorb certain wavelengths of light.
C. Any light that is not absorbed is reflected in all directions, like each point is a point source of light.
INSTRUCTIONAL ACTIVITIES:
(2) 1. Tell students that today we are going to talk about how we see color, and begin to explain that white light is "plain" light until it is colored by something.
(3) 2. Ask students for examples of how light gets colored. Students may begin to disagree already by this point.
(2) 3. Show students examples of how we "color" light with colored light bulbs, flashlights, and screens.
(2) 4. Demonstrate my example of light hitting a surface and becoming colored by the material.
(4) 5. I would assume that students would be protesting by this point that I am wrong. I will ask students to prove me wrong with their books, prisms, colored lights (of complimentary colors) colored markers, screens, and light sources with certain spectra such as Mercury and Helium.
(10) 6. The students work on solutions, and I offer "holes" in my theory as hints when necessary.
(4) 7. Ask students to come together with their reasons I am wrong.
(4) 8. Ask students to explain the properties of white light.
EVALUATION: Evaluate by asking students to give all of the correct properties of white light.
MATERIALS: Flashlights with colored cellophane over lens, prisms, markers, screens, Helium and Mercury light sources.
SOURCES:
Zitzewitz, Paul. Physics: Principles and Problems. (Westerville, Ohio: MacMillan/McGraw
Hill). 1992. Pp. 328-403
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AUTHOR: Cohen, Mark DATE: Dec. 10, 1997
COURSE NAME: Physics GRADE LEVEL: 11-12
UNIT TITLE: Optics CONCEPT: Image Formation
OBJECTIVE: The student will learn how lens principles can be used to focus light to make an image.
CONTENT:
I. In order to form an image something must focus light in one location.
A. Convex lenses focus light traveling through it to a spot called the focal point.
B. Small holes can act like lenses because they let through so few light rays. These light rays are traveling, for the most part, in the same direction.
II. Lenses have properties which are not necessarily intuitive.
A. When an image is formed by a convex lens it is flipped upside-down and backwards.
B. An image will form even if you block most of the lens.
C. For a given lens location, there is only one point at which the screen will have a clear image.
D. It is possible to see the image through the lens without a screen.
INSTRUCTIONAL ACTIVITIES:
(4) 1. The teacher will begin by asking the students if they know how their eye works.
(1) 2. The teacher will explain the components of the optical bench being used to simulate the eye.
(3) 3. The teacher will ask what happens if the lens is removed, remove the lens, and compare the predictions with the actual results. The teacher will ask the students to draw the rays of light from the source to the screen. The teacher will ask for the students to develop a principle about what happens to an image if there is no lens.
(2) 4. With the lens in place, the teacher will ask what will happen if a pencil is passed left to right in front of the lens. The teacher will compare the predictions to the results, and ask for a principle about the image formed by the lens.
(8) 5. The teacher will ask the students what they think will happen when half of the lens is covered. The teacher will then cover half of the lens, and compare the predictions to the results. If the students predicted something different from what they saw, can they now explain why they were wrong and how the light rays travel? The student will draw the path.
(4) 6. The teacher will cover the entire light source except for one small hole. The students will explain the pattern they see by comparing it to anything they have seen before. Is the pinhole a lens?
(3) 7. The teacher will ask what will happen if the screen is moved closer. The teacher will compare the results with the predictions. The teacher will ask why the image is clear at one spot.
(5) 8. The teacher will ask if the image can be seen without the screen. The students will have some time to try to see the image from any angle. The students will be left in suspense.
EVALUATION: The students will be evaluated on their ability to explain in words and on paper how light rays travel in the light-lens-screen system.
MATERIALS: Optical benches, convex lenses, large index cards, clear light bulbs, pencils, small index cards.
SOURCES:
Stewart, James E. (1991, November). The Mystery of the Negative Pinhole. The Physics Teacher, pp. 521-2.
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AUTHOR: Cohen, Mark DATE: Dec. 10, 1997
COURSE NAME: Physics GRADE LEVEL: 11-12
UNIT TITLE: Optics CONCEPT: Pinhole Lenses
OBJECTIVE: The students will work in teams to develop a pinhole camera.
CONTENT:
I. As light travels through a very small hole the light is "focused." If this light happens to fall on some sort of screen, the light will form an image.
A. The image from a pinhole is upside-down and backwards as with a lens.
B. The pinhole "lens" has no focal length.
INSTRUCTIONAL ACTIVITIES:
(4) 1. The students will be reminded of the previous lesson in which they used the optical bench in order to discover the properties of lenses. The students will review concepts from the day.
(3) 2. The students will be given the materials for making a pinhole camera, with little instruction. Their only instruction will be that they need to find a way to produce an image of a 40 watt light source they have at their desks.
(15) 3. The teacher will monitor the groups efforts. Occasionally an individual from a group will be allowed to travel to another group to "spy" on the construction of their camera.
(8) 4. The teacher will have each group give a brief synopsis of the reasoning behind the construction of their camera.
EVALUATION: Students will explain the reasons for the design of their camera, and the theory on which their camera design was based.
MATERIALS: Light sources, coffee can with translucent lid, 5 cm masking tape, #2 finishing nail, #8 common nail.
SOURCES:
Zitzewitz, Paul. Physics: Principles and Problems. (Westerville, Ohio: MacMillan/McGraw
Hill). 1992. Pp. 328-403
A. Mag-Lite
1. Inverse square law
2. Darken the room. Standing 75 cm from the chalkboard, shine a small Mag-Lite flashlight through a hole in a small piece of pegboard. Have a student make a square around the bright dot on the board. Calculate the area of the square. Back up to a distance of 1.5 meters and repeat. Students should observe that the area is four times larger though the distance only doubled.
3. (Zitzewitz, 1992, Physics, MacMillan/McGraw-Hill, p. 330)
B. Pinhole Camera
1. Pinhole lens, ray diagrams
2. Poke a hole in the bottom of a polystyrene cup with a thumbtack. Fasten a piece of waxed paper over the top with a rubber band. Darken the room and light a candle. Point the bottom of the cup at the candle and you can observe the candle's image on the waxed paper.
3. (Zitzewitz, 1992, Physics, MacMillan/McGraw-Hill, p. 332)
C. Coin in the Cup
1. Refraction of light
2. Put a coin in the bottom of a plastic cup. Have students back away from the cup until they can not see the coin anymore. Add water to the cup until the coin reappears. Ask students if they can explain how it happened.
3. (Zitzewitz, 1992, Physics, MacMillan/McGraw-Hill, p. 348)
D. Aquarium Reflection
1. Critical angle, total internal reflection, index of refraction
2. Fill a fish aquarium with water. Add fluorescent dye or milk to the water, and shine a laser light into the tank from the short side. Point the laser toward the water's surface (up), and adjust the angle until no light is being transmitted out of the top of the aquarium. Measure the angles to calculate the critical angle.
3. (Zitzewitz, 1992, Physics, MacMillan/McGraw-Hill, p. 351)
E. Fat Finger
1. Refraction
2. Obtain test tubes large enough for students to put their finger in with room to spare. Have the students fill the tubes with water, and observe the students' fat fingers.
3. (Zitzewitz, 1992, Physics, MacMillan/McGraw-Hill, p. 353)
F. Water Optics
1. Total internal reflection
2. Punch a small hole in the side of a 1 liter soft drink bottle. Fill the bottle with water and shine a laser into the bottle. Darken the room. The laser light exits the hole with the water, making the stream appear red.
3. (Zitzewitz, 1992, Physics, MacMillan/McGraw-Hill, p. 359)
G. Kaleidoscope
1. Reflection in mirrors
2. Give a student 2 plane mirrors set upright on hinges. Ask the student to bring the mirrors closer together by "closing the door." Have the student describe to the class what he or she saw. This is the way a kaleidoscope works.
3. (Zitzewitz, 1992, Physics, MacMillan/McGraw-Hill, p. 369)
H. The Car Mirror
1. Reflection, convex mirrors
2. Obtain a car's side mirror that says, "Objects are closer than they appear." Have students observe that the image is always right side up and smaller. Compare this to a concave mirror by passing one around the class.
3. (Zitzewitz, 1992, Physics, MacMillan/McGraw-Hill, p. 375)
I. The Magic Tube
1. Convex and concave lenses
2. Have students place a penny at the bottom of a test tube. Fill the test tube halfway with water. The penny looks small and far away because of the meniscus. Now fill the test tube to the top and keep adding water until there is a convex surface at the top. The penny will appear much larger and closer.
3. (Zitzewitz, 1992, Physics, MacMillan/McGraw-Hill, p. 381)
J. The Glass Block
1. Refraction, diffraction and interference
2. Shine a laser beam through a glass block, or any irregular piece of glass. Patterns will appear on the wall due to the refraction, diffraction, and interference of the light beam.
3. (Zitzewitz, 1992, Physics, MacMillan/McGraw-Hill, p. 392)
K. Ripple Tank
1. Double-slit interference, diffraction
2. Use a ripple tank to point out the interference between waves. Place the tank on an overhead projector and demonstrate the interference from two slits or two point sources.
3. (Zitzewitz, 1992, Physics, MacMillan/McGraw-Hill, p. 393)
L. The bumpy ruler
1. Diffraction
2. Mount a finely marked ruler horizontally. Darken the room and aim a laser beam so that it just grazes the ruler. Observe the diffraction pattern. Also try handkerchiefs, the eye of a needle, and wire gauze.
3. (Zitzewitz, 1992, Physics, MacMillan/McGraw-Hill, p. 401)
M. Air Interference
1. Interference
2. Mount two Plexiglas sheets close together so that there is a thin layer of air between them. Pressing down on the Plexiglas will cause patters of destructive and constructive interference.
3. (Crownson, 1996, Optics Unit Plan, p. 17)
A. Bending of Light
1. Index of refraction
2. On a piece of graph paper draw a line down the middle. With a felt tip pen, draw a line up the center of a semi-circular clear dish. This is the object. Place the dish along the straight line and trace the outline of the dish. Mark the position of the object on the paper. Fill the dish _ full. Lay a ruler on the bottom half of the paper until the edge of the ruler points at the object. Draw a line along the ruler edge to the dish. For the next part wipe the line off of the flat edge of the dish and draw a line in the center of the curved edge. Repeat the previous steps except put the ruler at the top half of the paper. The students can measure the incident and refracted angles, and then calculate the index of refraction for water.
3. (Zitzewitz, 1992, Physics, MacMillan/McGraw-Hill, p. 352)
B. Seeing is Believing
1. Virtual images from lenses
2. Using two small balls of clay secure a concave lens and a nail to a table surface. Set two small rulers in a Y pattern with the nail and lens. Look through the lens to make sure you can see both ends of the nail. Line up the 1st ruler to point at the head of the nail. Draw the line of sight. Move to the other ruler and do the same. Then, repeat these steps for the tip of the nail. Using a clean sheet of paper, repeat the entire procedure for a convex lens. Use these lines of sight to calculate the location of the virtual images.
3. (Zitzewitz, 1992, Physics, MacMillan/McGraw-Hill, p. 379)
C. Derive the Equation
1. Lenses, thin lens equation
2. The students will be given the same optical bench setup as they used in the inquiry lesson a few days before (section 7, part C, number 2). This time they must find the relationship between focal length, object distance, and image distance. The students must use the scientific method to deduce the thin lens formula.
3. (Crownson, 1996, Optics Unit Plan, p. 17)
A. The principal of a high school has the responsibility of supervising all of his or her teachers to ensure all necessary precautions are being taken. In addition, he is responsible for the maintenance of the building from the sinks to the outlets. The principal has a responsibility to create effective emergency plans and that all of his faculty and students know them. He supplies first aid kits and fire extinguishers, fire blankets, etc.
The science department chairperson also has a supervisory position over teachers, though in more of a direct role. The department chair has a greater idea of what can cause hazards in the classroom, and is usually responsible for the stockroom. The department chair must inspect equipment regularly and report to the principal any dangerous situations.
The science teacher is in the best position to control the hazards in his or her room. Often times the teacher is the one to make a judgment call about a lab or a project. The teacher must not only provide activities with a reasonable margin of safety but also decide if the students are mature enough for a particular lab. The teacher is also responsible for informing the students of the hazards in the lab.
B. The unit of optics deals with a few potentially dangerous pieces of equipment. To begin, there are a lot of experiments with glass. Broken glass and it's cleanup can be dangerous. In addition to glass, there is the danger of overexposure to laser light. Permanent eye damage can result from misuse of laser equipment. Finally, one should always be careful when using equipment which uses wall current, such as a laser.
C. In the pinhole camera demonstration students can use candles or a lamp to form an image. In order to reduce risk of fire I would use light bulbs if possible over a candle. The aquarium and glass block demonstrations use laser light which is usually safe. In order to mitigate any possible danger I would inform the students that laser light is dangerously powerful and cannot be directly observed. Finally, there is the small risk of broken glass, which I have addressed.
A. For this part of the unit plan I choose to work with a paraplegic student. A paraplegic student is a student who does not have the ability to move their lower body. This requires them to use wheelchairs for mobility.
B. A student who is paraplegic might face physical barriers to learning which would not effect a more mobile person. Narrow walkways, high traffic zones, tall lab tables and desks, and lack of handicapped accessible buildings are some physical barriers to their learning.
C. One of the first things that I could to help accommodate a disabled individual would be to make sure the physical surroundings were conducive to their needs. Lower desks are an example. I would try to make all of the labs and demonstrations inclusive to this individuals' disability. Lastly, I would ask if there was anything I could do to help them, if they desired my help.
D. An enrichment activity for a gifted student might include the task of helping write labs and determine curriculum. The student could serve as a great source of feedback as to how the students feel in the class. The student could help assure that the teacher is keeping their topics relevant from this student's input.
E. A student with limited English proficiency may require after school help or tutoring. In addition, the school might have some resources, such as a teacher proficient in the student's native language, to assist the student. Most importantly, I would attempt to do whatever it was that they needed me to do in order to keep them going with the class.
A. I chose Physics: Principles and Problems from Macmillan as the text for this unit. I reviewed copies of other texts and none seemed to have the mathematical depth blended quite so well with the conceptual information. It has a readability of approximate 11th grade level, which is appropriate for the students in the course. The text has an excellent set of supplementary materials which can be adapted for a variety of uses from verification labs to inquiry lessons. The edition of the text I used has since been replaced, but there are not many differences in the editions.
B. The following items would be appropriate for the teaching of this unit. The prices for the following materials were taken from the 1996 CENCO catalog, so all prices are considered approximate. Some items will be required in larger numbers. Some of these items are best purchased elsewhere besides CENCO science supply. After all, ten dollars for a flat mirror is ridiculous.
One Meter Optical Bench $24.75
Lamp Base $10.25
Glass block $16.10
5cmx5cm mirror (flat) $9.95
Convex lenses $3.95-$5.25
Diffraction gratings $24.00
He-Ne Laser $339.00
A. A process skill which could be assessed is the ability to create an image using lenses. This calls into the foreground a lot of the content covered in the unit as well as the ability to conceptualize the path of light rays. The student would need an optical bench setup similar to the demonstrations and labs.
B. An assessment tool which I would use to assess dispositions would be the essay. If a student can put their thoughts on paper clearly they are approaching scientific literacy. An open-ended essay question, about safety for example, gives the teacher a way of looking at the way a student thinks.
C. A surface learner might feel comfortable with a multiple choice or matching assessment. A deep learner might look for problems to solve or essay questions. Finally, a visual learner would look for some type of visual clue, guide, or schematic to guide him or her through the test. In optics, we could have a multiple choice on the properties of lenses, an essay question on the properties of the two types of lenses, or require a drawing of a optical bench setup.
A. This unit plan has the goal of teaching the content of optics as well as increasing scientific literacy in the students in accordance with the Illinois State Goals for Learning. The concepts and basic vocabulary of physical science are addressed in the presentation of words like diffraction and interference. For every term in this unit plan there are multiple ways of demonstrating its usefulness in society. Lenses are associated with devices, for example, and this knowledge is basic to our technical society. Social implications of optics are mentioned frequently, as well as the limitations of optics. Through inquiry this unit plan develops the principles of the scientific method in the students, and through experimentation and "hands on" experience the students gain knowledge of the techniques and technology in the sciences.
B. This unit plan, as stated above, is conducive to an inquiry approach to learning with the goal of enhancing the students' scientific literacy as suggested by the National Science Education Standards. By using multiple approaches such as cooperative learning and student directed learning this unit helps facilitate all students' learning. In addition to having a wide variety of approaches to accommodate different learning styles, variety helps keep the students challenged. Keeping goals for student achievement high is an important component in making students more scientifically literate.
C. Project 2061 uses a term called "scientific habits of mind." I think that this term does well to define scientific literacy and its goals for high school aged students. In this unit we address the physical setting, in the fourth chapter of the Project 2061 recommendations. This unit relates closely to the benchmarks on energy transformations, which is a small part in the greater concepts of matter, energy, force, and motion. As stated in Project 2061, it is the goal of this unit to, "use models to explain a vast and diverse array of natural phenomena"
I believe...
that students must be able to apply a concept to understand it. An idea with no application is like an automobile without any tires. We must keep our teaching relevant to student needs. This means never standing still.
that human beings must possess knowledge in order to be the masters of their own fates. Just as a saw cannot cut if the blade is not kept sharp, the individual will lose their effectiveness if they allow their minds to atrophy.
that an educated individual possesses qualities such as sensitivity, empathy, respect, and knowledge which light the lives of those around him.
that a teacher coordinates mental growth and attitudes toward academics in his or her students; an immense responsibility.
that a teacher's job is to do the best that they can to enrich the lives of the 150 or so students that go in and out of their door every day.
that I will always strive to improve my teaching and my own attitude. Not for my sake- but for those whom I serve.
American Association for the Advancement of Science. (1995) Project 2061- Science for All Americans. Washington, DC.
Arons, A. B. (1990) A guide to introductory physics teaching. New York, NY: John Wiley & Sons.
Bybee, R & Trowbridge, L. (1990) Teaching Secondary School Science. Englewood Cliffs, NJ: Prentice Hall
Crownson, Stephen. (1996) Optics Unit Plan. Illinois State University.
Faughn, J. & Kuhn, K. (1976) Physics for people who think they don't like physics. Philadelphia, PA: W. B. Saunders Co.
Stewart, James E. (1991, November). The Mystery of the Negative Pinhole. The Physics Teacher, p. 521-2.
Zitzewitz, Paul. Physics: Principles and Problems. (Westerville, Ohio: Macmillan/McGraw Hill). 1992. p. 328-403