Lesson Lunar Learning:
Moon Phases Always on the Move

Quick Look

Grade Level: 3 (3-6)

Time Required: 1 hour

(plus an advance observation homework assignment for students over the course of a month)

Lesson Dependency: None

Subject Areas: Earth and Space, Physical Science

NGSS Performance Expectations:

NGSS Three Dimensional Triangle

A photograph shows a gray round Moon in a black sky with one arc-ed edge of the moon (a crescent shape) glowing white and bright.
Crescent Moon.
Copyright © home.uchicago.edu/~sgee/


Everyone has gazed at the Moon, but why does it not always look the same to us? Sometimes it is a big, bright, circle, but, other times, it is only a tiny sliver. Students create Moon Logs to record and sketch how the Moon looks each night in the sky. With these first-hand observations, they are ready to figure out how the continuously changing relative positions of the Moon, Earth and Sun result in the different shapes and sizes. These different appearances of the Moon—its phases—change periodically over the course of the 28-day lunar month. A lesson demonstration using a golf ball, softball and basketball, along with a flashlight, serves as a model to aid in comprehension. Then, in the associated activity, student pairs use Styrofoam balls and lamps to act it out, reproducing the Moon phases.
This engineering curriculum aligns to Next Generation Science Standards (NGSS).

Engineering Connection

The Apollo moon landings were one of the most important engineering achievements of the 20th century, and a thorough understanding of the dynamic positions of the Earth, Moon and Sun relative to each other in space made it possible.

Learning Objectives

After completing this lesson and activity, students should be able to:

  • Identify the cyclic phases of the Moon.
  • Explain the positioning of the Earth, Moon and Sun at each phase.
  • Distinguish between waxing and waning.

Educational Standards

Each TeachEngineering lesson or activity is correlated to one or more K-12 science, technology, engineering or math (STEM) educational standards.

All 100,000+ K-12 STEM standards covered in TeachEngineering are collected, maintained and packaged by the Achievement Standards Network (ASN), a project of D2L (www.achievementstandards.org).

In the ASN, standards are hierarchically structured: first by source; e.g., by state; within source by type; e.g., science or mathematics; within type by subtype, then by grade, etc.

NGSS Performance Expectation

MS-ESS1-1. Develop and use a model of the Earth-sun-moon system to describe the cyclic patterns of lunar phases, eclipses of the sun and moon, and seasons. (Grades 6 - 8)

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This lesson focuses on the following Three Dimensional Learning aspects of NGSS:
Science & Engineering Practices Disciplinary Core Ideas Crosscutting Concepts
Develop and use a model to describe phenomena.

Alignment agreement:

Patterns of the apparent motion of the sun, the moon, and stars in the sky can be observed, described, predicted, and explained with models.

Alignment agreement:

This model of the solar system can explain eclipses of the sun and the moon. Earth's spin axis is fixed in direction over the short-term but tilted relative to its orbit around the sun. The seasons are a result of that tilt and are caused by the differential intensity of sunlight on different areas of Earth across the year.

Alignment agreement:

Patterns can be used to identify cause and effect relationships.

Alignment agreement:

Science assumes that objects and events in natural systems occur in consistent patterns that are understandable through measurement and observation.

Alignment agreement:

NGSS Performance Expectation

MS-PS2-4. Construct and present arguments using evidence to support the claim that gravitational interactions are attractive and depend on the masses of interacting objects. (Grades 6 - 8)

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This lesson focuses on the following Three Dimensional Learning aspects of NGSS:
Science & Engineering Practices Disciplinary Core Ideas Crosscutting Concepts
Construct and present oral and written arguments supported by empirical evidence and scientific reasoning to support or refute an explanation or a model for a phenomenon or a solution to a problem.

Alignment agreement:

Science knowledge is based upon logical and conceptual connections between evidence and explanations.

Alignment agreement:

Gravitational forces are always attractive. There is a gravitational force between any two masses, but it is very small except when one or both of the objects have large mass—e.g., Earth and the sun.

Alignment agreement:

Models can be used to represent systems and their interactions—such as inputs, processes and outputs—and energy and matter flows within systems.

Alignment agreement:

  • Models are used to communicate and test design ideas and processes. (Grades 3 - 5) More Details

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  • Recognize the major components and patterns observed in the earth/moon/sun system. (Grade 3) More Details

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  • Explain the causes of day and night and phases of the moon. (Grade 4) More Details

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  • Explain the monthly changes in the appearance of the moon, based on the moon's orbit around the Earth. (Grade 4) More Details

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  • Understand the earth/moon/sun system, and the properties, structures and predictable motions of celestial bodies in the Universe. (Grade 6) More Details

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  • Explain how the relative motion and relative position of the sun, Earth and moon affect the seasons, tides, phases of the moon, and eclipses. (Grade 6) More Details

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Everyone has gazed at the Moon. Have you ever wondered why it appears to change shape?

The week before presenting this lesson, give students a preliminary assignment of viewing the Moon at night with their parents. Have them record what they see each night in a "Moon Log." If you wish, have them also take pictures or make sketches of what they see each night. Also, have them find and cut out pictures of the Moon from magazines and newspapers, pasting them into the back of their Moon Logs.

On the day of the lesson, begin by dividing the class into groups of four or five students each. Within the groups, have them share the pictures and observations from their Moon Logs. Ask them why some of the pictures show the Moon as a circle and others show it as a crescent.

Give each group a golf ball for the Moon, a softball for the Earth, and a basketball and a flashlight if available for the Sun. Do this as a class demonstration as well. Encourage students to speculate on the positions of each for different phases of the Moon using their prior knowledge and observations from the Moon Logs. Then, open the discussion up to the entire class and discuss their theories. As concepts come up, introduce the appropriate vocabulary. Following the lesson, refer to the associated activity Lunar Lollipops: Reproducing the Moon Phases to help illustratemovement and placement of the Sun, Earth and Moon that creates the phases of the Moon.

Lesson Background and Concepts for Teachers

A diagram shows the different phases of the Moon relative to the Earth.
The phases of the moon.
Copyright © zebu.uoregon.edu/ ph121/l4a.html

The Earth has only one moon that orbits about it, due to the pull of gravity. The same side of the Moon faces the Earth at all times because the time it takes the Moon to spin once on its axis is the same as the time it takes for the Moon to orbit the Earth once. Because the Moon orbits the Earth and changes its position relative to the Earth and Sun, it appears to have a different shape each night – we call these the phases of the Moon.

The Moon shows progressively different phases as it moves along its orbit around the Earth. The phases of the Moon depend on how much of the sunlight can be reflected off the Moon at any one time. In the phase called the new Moon, the face is completely in shadow. About a week later, the Moon is in first quarter, resembling a luminous half-circle; another week later, the full Moon shows its fully lighted surface; a week afterward, in its last quarter, the Moon appears as a half-circle again.

The entire cycle is repeated each lunar month. The Moon is full when it is farther away from the Sun than the Earth; it is new when it is closer. When it is more than half-illuminated, it is said to be in gibbous phase. The Moon is said to be waning when it progresses from full to new, and to be waxing as it proceeds again to full.

Temperatures on the Moon's surface are extreme, ranging from a maximum of 127 °C (261 °F) at lunar noon to a minimum of –173 °C (–279 °F) just before lunar dawn.

A diagram shows the different cycles of the Moon, with the location of the Sun and the Earth indicated: first quarter, waxing crescent, new, waning crescent, third quarter, waning gibbous, full.
The phases of the Moon.
Copyright © csep10.phys.utk.edu/.../ lect/time/moonorbit.html

Associated Activities

Lesson Closure

What have we learned about the Moon?

The Moon can be seen from Earth because it reflects the light of the Sun back to Earth. Because the Moon orbits the Earth, it is positioned differently in relation to the Sun each night. Thus, different shapes of the Moon are reflected back to Earth. These are the phases of the Moon. There are eight phases: new Moon, waxing crescent, first quarter, waxing gibbous, full Moon, waning gibbous, last quarter, waning crescent.

Fun Lunar Trivia

  • Tides are caused by the Moon's gravity pulling the ocean and the Earth towards it. The Moon's pull forms a bulge of water on the side of Earth nearest to the Moon as well as on the opposite side of the Earth. These bulges of water move around the Earth to follow the Moon and thus create the tides.
  • The term blue moon is used to express the rarity of an occurrence. A blue moon is when two full Moons occur within one month and thus does not happen very often.


axis : An imaginary line about which something spins. For the Earth, it is a line extending between the north and south poles.

crescent moon: When only a small lit edge of the Moon can be seen.

full moon: The phase when the entire lit side of the Moon is visible.

lunar eclipse: A lunar eclipse occurs when the Earth's shadow blocks sunlight from reaching the Moon. At night, the moon appears dark instead of light when it should be a full Moon.

moon: The name given to the natural satellite of the Earth, and sometimes applied to the satellites of the other planets in the solar system

new moon: The phase when the entire Moon appears dark because the Sun is lighting the opposite side.

phases : The different shapes the Moon seems to have in the sky.

revolution: The movement of one object around another object.

rotation: The spinning of an object on its axis.

solar eclipse: When the Moon passes between the Earth and the Sun, blocking sunlight from reaching the Earth.

waning : The lit portion of the Moon is decreasing, progressing from full Moon to new Moon; this is when the Moon is "getting smaller" in the night sky.

waxing: The lit portion of the Moon increasing, progressing from new Moon to full Moon; this is when the Moon is "getting bigger" in the night sky.


Verify that students are able to explain why the Moon has different shapes at different times during the month using the appropriate vocabulary. Expect students to have constructed their own understanding of the concept through using models, drawing pictures and acting out the phases of the Moon.


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Clarke, Phillip, Corinne Henderson, Laura Howell, Kirsteen Rogers and Alastair Smith. The Usborne Internet-Linked Science Encyclopedia. London, UK: Usborne Publishing Ltd., 2002.

Graham, Ian. The Best Book of the Moon. New York, NY: Kingfisher, 2005.

Simon, Seymour. The Moon. New York, NY: Simon & Schuster, 2003.


© 2013 by Regents of the University of Colorado; original © 2004 Duke University


Teresa Tetlow; Catie Liken

Supporting Program

Engineering K-PhD Program, Pratt School of Engineering, Duke University


This content was developed by the MUSIC (Math Understanding through Science Integrated with Curriculum) Program in the Pratt School of Engineering at Duke University under National Science Foundation GK-12 grant no. DGE 0338262. However, these contents do not necessarily represent the policies of the NSF, and you should not assume endorsement by the federal government.

Last modified: June 17, 2019

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