Why Does the Moon Have Phases?

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In this activity, learners use a simple 3D model to discover why the Moon has phases. This activity is a very rewarding "ah-ha!" moment for learners since it helps to correct one of the biggest misconceptions about the night sky.

Note: this activity needs to be done outside during the day when the Moon is visible in the sky. The Moon will be visible in the morning a few days after full to a few days after last quarter and in the afternoon a few days before first quarter to a couple days before full.

Quick Guide

Preparation Time:
Under 5 minutes

Learning Time:
10 to 30 minutes

Estimated Materials Cost:
$5 - $10 per group of students

Age Range:
Ages 6 - adult

Resource Types:
Activity, Demonstration, Lesson/Lesson Plan


Materials List (per group of students)


  • Earth and Space Science
    • Astronomy
    • Earth, Moon and Sun
      • Days
    • Solar System
      • The Sun
      • The Moon
  • Mathematics
    • Geometry
    • Number and Operations
      • Fractions

Informal Categories

  • Model Building
  • Outdoor Activity


To use this activity, learners need to:

  • see
  • be mobile

Learning styles supported:

  • Uses STEM to solve real-world problems
  • Involves hands-on or lab activities


Components that are part of this resource:

This resource is part of:

Access Rights:

  • Free access



  • All rights reserved, Astronomical Society of the Pacific, 2008