Learn on PengiAmplify Science (California) Grade 8Chapter 1: Light and Dark on the Moon

Lesson 1: Pre-Unit Assessment

Key Idea.

Section 1

The Lunar Appearance Mystery

Key Idea

When observing the Moon, we see a sharp, curved boundary separating the bright, lit portion from the dark portion. This border is technically known as the terminator.
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Over time, the shape of the lit portion changes drastically. Sometimes the Moon appears fully round, sometimes it is a thin crescent, and other times it seems to disappear completely.

The central challenge of this unit is to explain these changing patterns. Since the Moon is a solid rock sphere that doesn't change shape, the changing light patterns must be caused by the way light interacts with it in space.

Section 2

Light Travels in Straight Lines (The Physics Rule)

Key Idea

To solve the mystery, we must first establish a basic physical principle: Light travels in straight lines.

The Sun acts as a powerful light source, sending energy outward in all directions. Because light rays travel in perfectly straight paths, they cannot curve around objects.

Lesson overview

Expand to review the lesson summary and core properties.

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Section 1

The Lunar Appearance Mystery

Key Idea

When observing the Moon, we see a sharp, curved boundary separating the bright, lit portion from the dark portion. This border is technically known as the terminator.
>
Over time, the shape of the lit portion changes drastically. Sometimes the Moon appears fully round, sometimes it is a thin crescent, and other times it seems to disappear completely.

The central challenge of this unit is to explain these changing patterns. Since the Moon is a solid rock sphere that doesn't change shape, the changing light patterns must be caused by the way light interacts with it in space.

Section 2

Light Travels in Straight Lines (The Physics Rule)

Key Idea

To solve the mystery, we must first establish a basic physical principle: Light travels in straight lines.

The Sun acts as a powerful light source, sending energy outward in all directions. Because light rays travel in perfectly straight paths, they cannot curve around objects.