Oreo Moon Phases
Modeling the Lunar Cycle with Cookies
Learning Objectives
Identify and name all eight phases of the lunar cycle in order
Create physical models that accurately represent the illuminated and shadowed portions of the Moon during specific phases
Explain why the Moon appears to change shape as viewed from Earth
Distinguish between waxing and waning phases based on the direction of illumination
Introduction: Why Does the Moon Change Shape?
~3 minutesWhy Does the Moon Change Shape?
The Moon does not produce its own light. What we see when we look at the Moon is sunlight reflecting off its surface. As the Moon orbits Earth (approximately every 29.5 days), the angle between the Sun, Earth, and Moon changes. This changing angle means we see different amounts of the Moon's sunlit side from our perspective on Earth.
These changing appearances are called phases of the Moon. There are eight distinct phases in the complete lunar cycle.
The Eight Moon Phases
~7 minutesThe Eight Moon Phases
New Moon: The Moon is between the Sun and Earth. The sunlit side faces away from us, so the Moon appears dark or invisible.
Waxing Crescent: A thin sliver of light appears on the right side. "Waxing" means growing larger.
First Quarter: The right half of the Moon is illuminated. This is called "quarter" because the Moon is one-quarter of the way through its cycle.
Waxing Gibbous: More than half of the Moon is illuminated on the right side. "Gibbous" means swollen or rounded.
Full Moon: The entire face of the Moon visible from Earth is illuminated. Earth is between the Sun and Moon.
Waning Gibbous: More than half is still illuminated, but now the light is shrinking from the right side. "Waning" means getting smaller.
Third Quarter: The left half of the Moon is illuminated. The Moon is three-quarters of the way through its cycle.
Waning Crescent: A thin sliver of light remains on the left side before the cycle begins again with a new Moon.
Think of it this way: waxing means the light is growing (like waxing a car adds shine), and waning means the light is shrinking. In the Northern Hemisphere, the light grows from right to left and shrinks from right to left.
NASA Reference (Optional Projection)
~3 minutesFor additional visual reference and photographs of each moon phase, visit NASA's Moon Phases page. This resource includes real photographs of each phase taken from space and can be projected for the class during the activity. See the external resource EXT-001 included in this package.
Materials and Allergy Check
~2 minutesMaterials Needed
For each student:
• 4 Oreo cookies (Double Stuf recommended for easier sculpting)
• 1 plastic knife or craft stick
• 1 paper plate
• 1 sheet of paper (for labeling phases)
• 1 pencil
For the teacher:
• Pre-cut phase assignment slips (8 phases, 4 drawn randomly per student)
• A container or bag for random drawing
• Paper towels for cleanup
• Reference diagram of moon phases (projected or printed)
Oreo cookies contain wheat, soy, and may contain traces of milk. Check your class roster for food allergies before this activity. Students with allergies can use white modeling clay pressed into dark bottle caps or dark cupcake liners as a substitute. The learning outcome is identical.
Oreo Moon Phase Modeling Activity
~41 minutesTeacher Preparation
Before class, prepare the random phase assignment system:
1. Write each of the eight moon phase names on separate small slips of paper: New Moon, Waxing Crescent, First Quarter, Waxing Gibbous, Full Moon, Waning Gibbous, Third Quarter, Waning Crescent. 2. Make enough complete sets so each student can draw four slips. One approach: create one full set of eight slips per student, place each set in a small envelope or bag, and have students draw four slips without looking. 3. Alternatively, create a master bag with multiple copies of each phase and have students draw four slips one at a time. This means different students will get different combinations, which makes the share-out discussion richer. 4. Ensure each student gets exactly four phases. Duplicates should be returned and redrawn.
Post-Activity Assessment
~10 minutesMatch each moon phase name to its correct description:
Place the eight moon phases in the correct order, starting with the New Moon:
Why does the Moon appear to change shape over the course of a month?
If you see a Moon that is mostly illuminated but has a small dark area on its right side, which phase is it?
In your own words, explain why we see moon phases. Your answer should mention the Sun, Earth, and Moon and how their positions relate to what we see.
Expected length: 30-100 words
During waxing phases, the illuminated portion of the Moon is getting smaller each night.