Energy and Change Light Electricity Energy
Introduction
Questions to
think about
How we see
Reflection
Reflection
Bending mirrors
Images
Plotting rays
Ray paths
Calculations
Summary
Refraction
Colour
Conclusion
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Introductory activity: Reflection

How does viewing an image in a mirror affect your ability to perform a simple task?
What to use Strategies
Hints Large flat mirror (20 cm × 15 cm), a 'Star' sheet, one pencil, a stiff white piece of cardboard and a stopwatch.
What to do
  1. Read the instructions for the activity below and then, before you begin, read the instructions in the information box.
  2. Stand the mirror vertically on the bench so that it is facing you.
  3. Place the Star sheet on the bench in front of the mirror.
  4. Hold the sheet of cardboard horizontally in a retort stand so that you cannot directly see the Star sheet, but you can see it in the mirror.
    Drawing from mirror reflections
  5. Place a pencil on the cross on the star, and then, by looking only at the image in the mirror, move the pencil around the star without lifting it off the paper and without going outside the double lines.

  1. In a suitable table, such as the one shown, record:
    1. the time taken to go around the star
    2. the number of errors (number of times the pencil goes outside the double lines).
  2. Repeat the experiment several times (eg four) for each student and, each time, record the time taken and the number of errors.
  3. Change places with your partner so that each member of your group has their four trials with the Star sheet.
  4. You could present your results or the results of the group in the form of a graph, such as the one shown. Your teacher will discuss whether this should be a line graph or a bar graph.

    Record of drawing from mirror reflections

You might choose to average the readings for your group and so draw the two graphs showing the group results.
A graph of a sample of measurements taken

Instructions Strategies
Before beginning the activity, read the questions and discuss:

  1. What are you testing?
  2. Should you have all of your turns at once or should everyone in the group only have one turn at a time?
  3. Should you collect all the group results or all the class results to draw the graphs and to come to conclusions?

Discussion Strategies


  1. Why was the task more difficult than you thought it might be?
  2. How did your performance change with practice? What evidence do you have to show this?
  3. Compare the graphs from each person. How did the number of errors a person made compare with the time they took? How did it compare with the number of times the person had tried the test?
  4. Compare the rates at which each person improved their times with practice.
  5. Why is it not appropriate to average the results of the trials each person did?
  6. Question 6

Lateral inversion
Lateral inversion is the term used to describe the reversed image you observed in the plane mirror. The image appears to be flipped left to right.


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