Class Material and Lesson Plan
The lesson plan below is just an outline and suggested way to present the material. The target age group this demonstration was designed for is grade 6 and 7, so adjust the material accordingly to your age group. More advanced topics may include refraction, snell's law, characteristics of convex mirrors, and image formation fo mirrors.
1. Introduction
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Start off with an introduction about light. Some good points to cover are: representation of light as rays, properties of light rays
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Using a laser pointer, demonstrate that light can be shown to travel in a straight line. With a spray bottle, spray mist into the line of the laser to show the path of the laser
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Demonstrate that the laser will reflect off the square mirrors
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Once you have convinced your class that light travels in a straight line, and that it will reflect off mirrors, move on to the class activity
3. Demonstration
IMPORTANT: Make sure nobody looks directly into the lamp. It can be harmful to the eye and will be painful. If possible, accuire sunglasses for each student to wear while demonstrating; otherwise, look to the side of the light.
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Set up the demonstration as in the picture on the Materials page
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First demonstrate lighting the match. If you have trouble, colour the match head in with a pencil. Be patient! It may take around a minute and a half to light.
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Explain that at the match head, where the focal point is, light is reflected off the mirror and all collects there
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Move on to demonstrate other items, such as white paper, black paper, candles -- be creative!
2. Class Activity (Periscope)
Ideal groups of 2-3
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Distribute one wood plank and 2 square mirrors to each group
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Instruct students to find a way to arrange the mirrors so that they are able to see above and behind their heads, like a periscope. After a while, give hint: explain the law of reflection, and how light reflects off plane mirrors
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Continue with activity -- if some students are done early, ask them to find the following as well:
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above and in front
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to the side and behind
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to the side and in front
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Have students come up to the front of the class to explain how they obtained their results and see if there are other different arrangements for the same result
4. Discussion
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Discuss why objects in the focal point will get hot
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Light gets absorbed into materials depending on what colour they are -- black absorbs all the light shining on it
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Light contains energy. When it is absorbed into an object, the energy from the light must be converted to some other form of energy and be expelled from the object -- Law of Conservation of Energy
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White reflects (mostly) all light and therefore will not absorb energy
Conclusion
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Review how light travels in straight lines and will reflect off mirrors
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Review focal points, what they are, and how why they are important
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Review how light can be transformed into heat energy