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Reflection:
Teacher Notes
MA.7.G.4.2
MA.912.G.2.3
Conceptual Knowledge
Transformations
Reflections
Coordinate Plane
Procedural Knowledge
Graphing Points
Making Transformations (Flips, Slides, Turns)
Problem Solving
Reasoning
Communication
Connections
Representation
Look in the mirror. Raise
your right hand. Does your reflection also raise its right hand?
Students work individually.
Each student needs:
- 3 sheets of graph paper
- 1 ruler
- color pencils
- protractors
- stencils (see attached)
- Trace the stencil on one side of the x-axis. Press hard with your
pencil so your figure can be seen through a folded page. Now mark
three points on the figure. Label them A, B, and C.
- Fold the first sheet of paper along the x-axis for a horizontal
line of reflection.
- On the back of the graph paper trace the figure, including A, B,
and C. Press hard with your pencil. Open the paper and trace that
reflection on the front.
- Locate the images of A, B, and C in the reflected figure. Label
the points A', B', and C'.
- Use a straightedge and a red pencil to connect A to A', B to B',
and C to C'.
- Measure the angles where the line of reflection crosses each red
segment. What do you observe?
- Mark the midpoint of each of the red segments. What do you observe?
- Find the coordinates of A, B, and C and A', B', and C'. What do
you observe?
- Do numbers 1-8 using the y-axis as a vertical line of reflection.
- Do number 1-8 using the graph of y=x as a diagonal line of reflection.
As a result of this activity,
students will learn that some transformations, such as reflections
and rotations, do not change the figure itself, only its position
or orientation.
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