1. Reflection is Key: A periscope uses two mirrors, angled at 45 degrees, to redirect light.

2. Light Enters: Light enters the periscope through the top opening.

3. First Reflection: The first mirror, angled at 45 degrees, reflects the light beam horizontally. This mirror is positioned at the top of the periscope, facing downwards.

4. Traveling Through the Tube: The light beam travels horizontally through the periscope's tube.

5. Second Reflection: The second mirror, also at 45 degrees, reflects the light beam vertically upwards. This mirror is positioned at the bottom of the periscope, facing upwards.

6. Exiting the Periscope: The light beam exits the periscope through the bottom opening, allowing you to see an object that's located above the periscope's height.

In Simple Terms: Imagine light as a bouncy ball. The mirrors act like tilted surfaces that bounce the light beam, changing its direction. This allows you to see things that are out of your direct line of sight.