Activity 2
(alternate steps)

When you look into your model kaleidoscope, the images you see are caused by light rays reflecting from the confetti, striking the hinged mirrors, then bouncing off the mirrors into your eyes.  As you change the positions of the mirrors, the paths of the light rays also change. In this activity, you explore the paths that light rays follow in a reflection.
 
Exploration 

a.	Label an x-axis and a y-axis on your sheet of graph paper.  Label the origin (0,0) as point A and a point towards the end of the positive x-axis as point B. 

b.	Place the graph paper on a piece of corkboard.  Place the hinge of a hinged mirror on the origin and hold one mirror firmly on the positive x-axis and the other firmly on the negative y-axis. 

A (  ,  )								B  (  ,  )		X	

													
			P  (  ,  )								
													
							Q  (  ,  )				

													
													
Y													

c.	Point A must be at the origin.  Label the coordinates of Points A and B. 

d.	1.	Choose a point with a positive x-coordinate from three to five and a negative y coordinate from –3 to –7.  Its coordinates are  (___,___)  Label it P.

2.	Choose a second point 3 or more units to the right of point P with a negative y coordinate from –3 to –7.  Its coordinates are (___,___)  Label it Q.

e.	1.	Place one pushpin through P and another through Q.
	
2.	At eye level, sight through P toward the mirror with one eye closed.  Looking at the reflection of Q, move your head until P aligns with the image of Q.

	3.	Mark a point C on the x-axis where P, C, and the reflection of Q are collinear (on the same line).

f.	Place a rubber band around the two pushpins.  Using the point of a pencil, pull the side of the rubber band closer to the mirror until the pencil is at C.  Check the position of C again to make sure P, C, and the reflection of Q are collinear.  The side of the rubber band you stretched shows the path that light rays follow from Q to the mirror to P. 

g. 	1.	Remove your graph paper from the board.  Draw PC and CQ.  These segments show the path of light as it travels from the pushpin at Q to your eye at P by reflecting off the mirror.   

2.	Measure <QCB and <PCA.  Record these angle measures. 

	3.  	Save your graph paper for use in the assignment and in Act 3.

		<PCA		<QCB					<PCA		<QCB	
Group 1	____		____			Group 2	____		____
Group 3	____		____			Group 4	____		____
Group 5	____		____			Group 6	____		____
Group 7	____		____			Group 8	____		____