ZERO-IN

Italicized font represents information to be shared orally or physically completed with the students at this time.

The non-italicized font represents additional information included to support the teacher’s understanding of the content being introduced within the CELL.

ANALYZE IT

Instruct students to complete the Analysis Questions in their SDRs then discuss them as a class. Use the suggested responses below to guide students’ answers.

• How would you describe the Law of Reflection? The Law of Reflection states that the angle of incidence or the angle at which light strikes an object equals the angle of reflection or the angle at which light is reflected off of the object.

• What evidence did you find in your experiment that supports the Law of Reflection? Students should indicate that in the experiments with the flashlight and mirror when the beam of light struck the mirror at a 60°, 25° or 0° angle it was reflected at a 60°, 25° or 0° angle, respectively. In addition, in the experiment with the bear, cave and mirrors, for each mirror used to reflect the image of the bear to the mirror at the back of the cave, the angle of incidence was equal to the angle of reflection.

Note: In the bear and cave activity, students may report angles of incidence and reflection that are very similar but not identical. The sample data provided in question 16 e (and above) shows such an example. Discuss with students possible reasons for this discrepancy such as slight variations in locating the center of each mirror, and slight movement of the mirrors when drawing lines. Include in the discussion that the small differences between the angles of incidence and reflection would be within the experimental margin of error for this experiment.

GET FOCUSED

Instruct students to complete the Focus Question in their SDRs then discuss it as a class. Use the suggested response below to guide students’ answers.

• How does light wave interact with objects that reflect light? Objects that neither absorb nor transmit light reflect light. When a light wave interacts with an object that reflects light, the angle at which the wave is reflected off the object (the angle of reflection) is equal to the angle at which it encounters the object (the angle of incidence). This is true regardless of the angle at which the wave strikes the object. This relationship is called the Law of Reflection.