MIRROR LEARNING CYCLE

 

TARGET CONCEPT: (not shown to the students)

                  The angle of incidence equals the angle of reflection.

 

PRECONCEPTION: (what students may think)

Objects have to be at right angles with each other or the mirror has to be in the center between the people.

 

GEAR-UP:

Two people (select two about the same height) stand on masking tape facing a wall.

Is there a place where I can put this so that one can see the other? (don't talk about it; just have people make their own individual predictions.

Individuals make predictions as to where to place the mirror - Post-its with their initials.

The two people who are standing should also get a chance to make predictions.

As they are making their predictions, suggest some other questions they might be thinking about.

         •       Is there more than one place to put the mirror?

         •       Is there a place where both can see each other?

         •       Is there a way to predict where to put the mirror?

 

EXPLORE: group work

What can you discover about where a mirror needs to be for two people to see each other?

 

GENERALIZE:

Groups report back by making a group prediction and demonstrate how they did their work.

Possible teacher questions during the group feedback.

•       Some people say that the people have to be a right angles to each other in respect to the mirror - what do you think of that?

•       Are there any cases where right angles work?

•       Are there any cases where right angles do not work?

•       With the mirror in the same position, is there another set of two places where they could stand and still see each other?

•       Are there different ways two people can move and still see each other without moving the mirror?

 

EXPLORE:

Explore all the different ways two people can move so that they can see each other in a mirror.

 

GENERALIZE:

Groups prepare an overhead to report their findings. Teacher keeps tally of different directions on chalkboard.

Possible teacher questions during the group feedback.

•       Is there anything special about the relationship between A and the mirror and B and the mirror? Do you have a theory?

•       How did you explore?

•       How are the group presentations similar; how, different?

EXPLORE:

There has been a lot of the use of the word "angle." How can we describe all the ways A and B can be placed and see each other without using the "a" word?

 

GENERALIZE:

Groups report back. (Talk informally about what you discovered when you tried to get rid of using this word - difficulties, new discoveries, group consensus on meanings.)

 

EXPLORE:

What is a reflection?

 

GENERALIZE:

Groups report back their discussions.

Possible teacher questions during the group feedback.

•       Is there a generalizable rule for seeing reflections in a mirror?

•       What is the role of light in reflections?

•       How does the light get from A to B and visa-versa?

•       Is there any special way the light bounces off the mirror?

 

EXPLORE:

"When talking about reflections, physicists say that the angle of incidence (light going into a mirror) equals the angle of reflection." How does this statement relate to your discoveries. Challenge some groups to we prove this using string and meter sticks only (no protractors allowed)

 

GENERALIZE:

Groups report back their discussions, showing details on board. Some groups are asked to show their proof using string and metric rulers on the floor.

 

POSSIBLE APPLICATIONS:

1) Keeping in mind everything we have explored about mirrors, write your name so that you can read it in a mirror.

•       Try to do it first by looking in the mirror and making your pen go the way it should.

•       Then try it by thinking about reflections and how they work.

•       What did you discover?

 

2) Explore an aspect of mirrors - a question or fun observation - at home and draw or diagram your observations and show how you think your discovery either demonstrates or refutes the "rule." Share with class next week.

 

3) Explore a curved mirror. Try to draw a diagram which illustrates why object appear smaller in this mirror than they do in regular mirrors. Does the "rule" apply to these mirrors?

 

4) Can you think of an explanation for the distortions in the images from some reflective surfaces. Use a diagram to help.

 

5) Some people say that what bats do with sonar could be related to the way we see? What do you think about this? Do some research if you'd like. Draw diagrams if helpful.

 

6) Some people say you can see your whole body in any mirror as long as you stand far enough away. Others say that a mirror has to be a certain size? What do you think and why? Draw diagrams to help in your explanation.

 

ASSESSMENT:

Ask students to complete a worksheet on which several cases of A and B and the mirror are given (some clearly equal angles, some clearly not equal, some questionable). Ask students in which cases A and B can see each other. Ask students to show the work they did to arrive at their prediction and explain their reasoning.

 

 

Note for differentiation: At any time if an individual or group can prove their theory with string and meter sticks, then have them explore one or more of the application challenges.