Lesson 2: Moon Phases and the Lunar Cycle

-How does the Moon’s position relative to Earth and the Sun create its phases?

-Why does the Moon appear to change shape over the course of a month?

-What is the difference between waxing and waning phases?

-How long does it take the Moon to complete a full lunar cycle?

-How can models and observations be used to predict the Moon’s phase on a given day?

-Why do we always see the same side of the Moon from Earth?

Lunar cycle

Moon phase

New Moon

Full Moon

Waxing

Waning

Crescent

Gibbous

First quarter

Third quarter

Orbit

Tidally locked

Reflective light

HS-ESS1-2 – Analyze data to describe the effects of Earth’s rotation and the Moon’s orbit on observed phenomena such as lunar phases.

HS-PS2-4 – Use models and gravitational interactions to explain orbital motion within the Earth-Moon system.

NGSS Crosscutting Concepts

-Patterns

-Cause and Effect

-Systems and System Models

-Scale, Proportion, and Quantity

Students will interpret diagrams and models showing the relative positions of the Sun, Earth, and Moon to determine and predict lunar phases.

Students will analyze lunar calendars and observational data to identify patterns in the lunar cycle.

Students will construct explanations using evidence from models to describe why the Moon appears to change shape over time.

Students will investigate how the Moon’s orbit around Earth produces observable phases over a repeating lunar cycle. Using models, simulations, and observational data, students will explore how the relative positions of the Sun, Earth, and Moon determine what portion of the Moon is illuminated from Earth’s perspective.

Activities may include:
-Modeling Moon phases using lamps and spheres
-Tracking the Moon’s phase over time using a lunar calendar
-Analyzing diagrams of Sun-Earth-Moon positions
-Using simulations to predict future Moon phases
-Comparing observational data to model predictions

Purpose: Develop understanding of cyclical patterns in the Earth-Moon system and reinforce the use of models to explain and predict astronomical phenomena.

DOK Level: 2–3 – Skill/Concept to Strategic Thinking (identifying patterns, applying models, and making predictions)

Students connect lunar phases to real-world observations such as nighttime visibility, cultural calendars, historical navigation, and traditions based on the Moon cycle.

Students explore how different cultures have used lunar cycles to organize time, agriculture, and religious observances.

Connections to modern astronomy, including how lunar phases affect satellite imaging and space missions.

Students may think the Earth’s shadow causes the phases of the Moon.

Students may believe the Moon produces its own light rather than reflecting sunlight.

Students may assume lunar phases happen because the Moon moves in and out of Earth’s shadow regularly.

Students may struggle to understand that the entire Moon is always half illuminated.

Students may confuse the order or sequence of lunar phases.

-Step-by-step modeling of Moon phases using physical objects

-Visual phase charts and labeled diagrams

-Graphic organizers showing Moon phase sequence

-Interactive simulations for reinforcement of spatial relationships

-Partner activities for predicting and checking lunar phases

-Chunked vocabulary support with visuals

-Formative checks during Moon phase modeling activities

-Quizzes on lunar cycle vocabulary and phase identification

-Student completion of Moon phase calendars

-Constructed-response explanations of how phases occur

-Diagram labeling assessments of Sun-Earth-Moon positions

-Exit tickets predicting future Moon phases based on a given date

-Lamps and spheres for modeling Moon phases

-Lunar phase charts and calendars

-Interactive simulations of Moon orbit and illumination

-Worksheets for tracking lunar cycles

-Diagrams of Sun-Earth-Moon system positions

-NASA lunar data resources or visualizations