Science · 5th Grade · Stars and the Solar System · Weeks 10-18

The Moon's Phases

Students will observe and explain the predictable patterns of the Moon's phases as it orbits Earth.

• Common Core State Standards
• 5-ESS1-2

About This Topic

The Moon's phases are the different ways the Moon appears to us from Earth over about a month. These changes are not caused by the Earth's shadow, but by how much of the sunlit side of the Moon we can see as the Moon orbits our planet. As the Moon travels around Earth, the angle between the Sun, Earth, and Moon changes, revealing different portions of the Moon's illuminated surface. Understanding this celestial dance helps students grasp concepts of orbital mechanics and light reflection.

This topic directly supports students' understanding of our solar system by illustrating the dynamic relationships between celestial bodies. It provides a tangible example of how perspective influences observation and lays the groundwork for comprehending other astronomical phenomena. By studying the Moon's phases, students develop critical thinking skills as they analyze patterns and construct explanations based on evidence from their observations. This scientific inquiry process is fundamental to all branches of science.

The Moon's phases are an ideal topic for active learning because students can directly observe the phenomenon over time and model the underlying mechanics. Engaging with physical models and tracking observations fosters a deeper, more intuitive understanding than passive listening or reading alone.

Key Questions

1. Explain the cause of the Moon's changing phases.
2. Predict the next phase of the moon given its current appearance.
3. Construct a model to demonstrate the relationship between the Earth, Moon, and Sun during different phases.

Watch Out for These Misconceptions

Common Misconception

The Earth's shadow causes the Moon's phases.

What to Teach Instead

This misconception can be addressed by having students build and manipulate a Sun-Earth-Moon model. Seeing that the phases change regardless of Earth's shadow helps them understand that it's about the viewing angle of the sunlit Moon.

Common Misconception

The Moon produces its own light.

What to Teach Instead

Through observation activities and model building, students can discover that the Moon only appears to shine because it reflects sunlight. Demonstrating this with a flashlight and a ball clarifies that the Moon does not generate light.

Active Learning Ideas

Model: Earth-Moon-Sun System

Using a light source (Sun), a ball (Moon), and a student's head (Earth), have students move the Moon ball around their head. They should observe and sketch how the illuminated portion changes as the Moon orbits.

30 min·Small Groups

Observation Log: Moon Journal

Students observe and sketch the Moon in the night sky (or a provided image) each evening for two weeks. They record the date, time, and appearance, noting any patterns.

10 min·Individual

Interactive Simulation: Phase Predictor

Use an online interactive simulation that allows students to manipulate the positions of the Earth, Moon, and Sun. They can then predict and verify the resulting Moon phase.

20 min·Pairs

Frequently Asked Questions

Why does the Moon look different each night?

The Moon's appearance changes because of its orbit around Earth. As the Moon moves, the angle at which we view its sunlit surface shifts. We see different amounts of the illuminated side, creating the cycle of phases from new moon to full moon and back again.

What is a 'new moon'?

A new moon occurs when the Moon is positioned between the Earth and the Sun. From Earth, the side of the Moon facing us is not illuminated by the Sun, making it appear invisible or very dark in the sky.

How can students best understand the cause of Moon phases?

Active learning, such as using physical models of the Sun, Earth, and Moon, allows students to physically demonstrate and observe how changing positions create the different phases. Tracking observations over time and discussing their findings solidifies this understanding.

Does the Moon orbit the Sun too?

Yes, the Moon orbits the Earth, and as the Earth orbits the Sun, the Moon travels along with it. This combined motion is what we observe in the night sky.