Try This Tops Idea!

Article excerpt

1. Poke half the length of a sharp pencil (or pen) through the center of an index card.

2. Hold some paper (on a firm backing) in front of a mirror. Adjust angles so you can see the pencil point in the mirror, but not in your hand.

3. Looking only in the mirror, draw a square crossed with diagonal lines.

4. Write your name so it looks normal in the mirror.

5. Why is this so hard to do?

Umm, I wonder if this qualifies as "normal ..."

OBJECTIVE

To experience the reversed nature of a reflected image. To have fun.

LAB NOTES

Copy the lab for each student or lab team. Decide how students will access available mirrors.

ANSWERS

5. Looking into a mirror, my brain must coordinate the hand with a visual image reversed from what it usually sees. (When the reflected object is in the horizontal plane, the image is upside down. If the object is in the vertical plane, its image is reversed left-to-right.) With my paper flat, I must move my pencil away from me to bring the reflected pencil toward me. My hand must do the opposite of what my eyes see happening.

MATERIALS

* An index card. Small works fine.

* A mirror. Prop a hand mirror on a table, or stand in front of a wall mirror. …