Demonstrating Moon Phases
Teacher’s Guide
Adapted from Lake Afton Public Observatory
Wichita, KS
Description: This demonstration will give students a chance to experience first-hand
the relative positions of the sun, Earth, and moon. By examining these positions, they
will discover why the moon goes through phases.
Objectives:
Students will:
 Observe how the moon goes through phases.
 Create a complete series of phases matching the appearance of the Moon.
 Relate moon phases to the positions of Earth and the Sun
Materials Needed:
1. Bright Light Source (bare-bulb on lamp stand works well)
2. Styrofoam ball (2" to 3" across) for each student
3. Pen or small stick (to mount Styrofoam ball)
Teaching Suggestions:
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Depending on the level of your class, you may decide to do
only a portion of this activity.
If you are only interested in demonstrating why the moon
goes through phases, it is only necessary to do the Motion
and Phase of the Moon section. This part of the activity
will take students through half of the moon's cycle -- new
moon to full moon.
If you are interested in having your students also know the
moon's position in the sky at each phase, then you should
complete the next activity as well.
Pre-activity
Before doing the activity, ask the class to list possible explanations for the phenomena
of moon phases. Try to avoid making comments on the validity of the theories offered.
Ask students to write down their own explanations, based on what they have heard.
After the activity, ask students to rewrite their explanations for moon phases and
discuss any changes from their previous ideas. Encourage students to do this activity at
home with their families or to model the moon phases for younger students and then
write about their results.
Introduction
Anyone that has watched the moon in the sky for a period of two weeks has
noticed that it seems to change its shape, from a thin crescent to a bright white ball.
These changes in the moon's shape or phase are due to the moon's motion around
Earth and how we view it.
The moon, like every object in the solar system, has half of its surface sunlit and
the other half dark. As the moon orbits Earth, we see different amounts of the moon's
sunlit half. At new moon the moon's sunlit half is facing away from us; at first quarter we
see half of the sunlit half; while at full moon, we see the entire sunlit half. At no time
does the shadow of Earth fall on the moon to cause its phases.
One of the difficulties with most models that demonstrate the phases of the moon
is that the student must imagine himself or herself standing on the ball which represents
Earth. In this activity the student's head is the Earth, a bright light source is the sun, and
a Styrofoam ball on a stick or pen held at arms length represents the moon.
Activity 1: Motion and Phase of the Moon
Procedure / Discussion Questions
1. Have your students place the Styrofoam ball on the
pen or small stick. This ball represents the moon.
Have them hold the ball so the light shines on it.
Q. Light is shining on how much of the ball?
A. Half of the ball is lit up.
Q. If the ball is held in a different place is more,
less, or the same amount of it covered with light?
A. Regardless of where the ball is held, half of it is
always light.
2. Now have them face the sun and hold the ball in
front of them.
Q. As they look at the ball do they see any of the light that is falling on it? They
should not see any of the light falling on the ball. Why don't they see light falling
on it?
A. The half of the ball that is lit is facing away from them.
3. Have them move the ball slowly to their left (counterclockwise).
Q. What begins to happen?
A. They should begin to see part of the ball's lighted half.
4. Have them start to move the ball.
Q. How far must the ball be moved before half of the lighted side is visible?
A. The ball must be moved one-quarter of the way around their head.
5. Have the students keep the ball moving.
Q. How long before all of the lighted side is visible?
A. Half-way around.
6. Have the students keep moving the ball in the same direction.
Q. What happens if you keep moving the ball in the same direction?
A. They begin to see less and less of the lighted half of the ball.
7. The bright light represents the sun and the Styrofoam ball represents the
moon. As the moon revolves around Earth we see different amounts of its sun lit
half. This causes the phases of the moon!


Q. Where is the moon in its orbit at:
a crescent?
A. About one-eighth of the way around
first quarter?
A. One-fourth of the way around


full moon?
third quarter?
 new moon?
A. Half way around
A. Three-quarters of the way around
A. Directly between the sun and Earth at the beginning of the cycle
Activity 2: Location of the Moon
Procedure / Discussion Questions
The position of the moon in our sky at different phases can be demonstrated. The
position of the sun and Earth will first be used to establish directions.
1. Have your students stand facing the sun (bright light).
Q. What time of day does this represent?
A. Since they are facing the sun, the sun is overhead in the sky. Thus it is noon.
Q. What direction are they facing?
A. South
Q. Which direction is to their left?
A. East
Q. Which direction is to their right?
A. West
2. Now have them turn so the sun sets.
Q. In which direction did they have to turn (left to right or right to left)?
A. In order to have the sun set in the western part of the sky, the students will
have to turn to their left.
3. Have the students think about what time they see the sun.
Q. What time is it when the sun is directly to their right?
A. Sunset / Midnight
Q. What time is it when the sun is directly to their left?
A. Sunrise
Q. What time is it when the sun is behind them?
A. Midnight
4. To get some idea of where the moon is in the sky at different phases have the
students turn so the sun is setting.
Q. What direction are they facing?
A. They are facing south.
Q. Left and right are what directions?
A. Left is east and right is west.
5. Now have them hold the moon so that it is in the same direction as the sun.
This is the new moon phase since the sun lit half of the moon is facing away from
us. Now have them move the moon in its orbit (to the left).
Q. What happens?
A. They begin to see part of the lighted half of the ball -- a crescent moon.
Q. In what direction should they look to see the crescent moon at sunset?
A. Southwest
6. Have the students move the moon so it is in front of them.
Q. What phase is this?
A. First Quarter
Q. In what direction is the moon?
A. Due south
7. Have the students continue until they reach full moon.
Q. In which direction should they look for a full moon?
A. In the east
Q. What happens if they move the moon further in its orbit?
A. It can no longer be seen.
Q. When should they look for it?
A. They must look for it later than sunset.
8. Repeat the above procedure, except have the students turn so the sun is rising.
Q. What direction are they facing now?
A. South
Q. What directions are right and left?
A. Left is east and right is west.
Q. Where should they put the moon in its orbit so that it is full?
A. On the opposite side of the sun, in the west.
9. Have them slowly move the moon in its orbit.
Q. How does the phase and position change?
A. As the moon moves toward the east, students will see less of the sunlit half.
Q. Why is this different from before?
A. Before they were seeing more and more of the sunlit half as the moon moved
from the west to east and now they will see less and less.
Additional Activity
This same kind of activity can be used to illustrate why the constellations appear to
move from east to west during the evening. Just have the students turn and notice that
objects in the room that were once to their left move in front of them and finally to their
right. The same thing happens with the constellations.
Credits: Adapted from the Lake Afton Public Observatory http://webs.wichita.edu/lapo/demon.html by the ASU Mars Education
Program (9/06)
Name____________________________________Date_________________________________
Demonstrating Moon Phases
Student guide
Adapted from Lake Afton Public Observatory
Wichita, KS
Activity 1: Motion and Phase of the Moon
Introduction
Anyone that has watched the moon in the sky for a period of two weeks has
noticed that it seems to change its shape, from a thin crescent to a bright white ball.
These changes in the moon's shape or phase are due to the moon's motion around
Earth and how we view it.
The moon, like every object in the solar system, has half of its surface sunlit and
the other half dark. As the moon orbits Earth, we see different amounts of the moon's
sunlit half. At new moon the moon's sunlit half is facing away from us; at first quarter we
see half of the sunlit half; while at full moon, we see the entire sunlit half. At no time
does the shadow of Earth fall on the moon to cause its phases.
One of the difficulties with most models that demonstrate the phases of the moon
is that the student must imagine himself or herself standing on the ball which represents
Earth. In this activity the student's head is the Earth, a bright light source is the sun, and
a Styrofoam ball on a stick or pen held at arms length represents the moon.
Pre-activity
Why does the moon appear to change shape or go through phases? There is no right
or wrong answer, just list your ideas below:
______________________________________________________________________
______________________________________________________________________
______________________________________________________________________
______________________________________________________________________
Procedure
1. Place the Styrofoam ball on the pen or small
stick. This ball represents the moon. Hold the ball
so the light shines on it.
Q. Light is shining on how much of the ball?
___________________________________________
Q. If the ball is held in a different place is more, less,
or the same amount of it covered with light?
___________________________________________
___________________________
2. Now face the sun and hold the ball in front of you.
Q. As you look at the ball do you see any of the light that is falling on it? Why don't
they see light falling on it?
______________________________________________________________________
3. Move the ball slowly to your left (counterclockwise).
Q. What begins to happen?
______________________________________________________________________
______________________________________________________________________
4. Start to move the ball.
Q. How far must the ball be moved before half of the lighted side is visible?
______________________________________________________________________
Q. How long before all of the lighted side is visible?
______________________________________________________________________
______________________________________________________________________
6. Keep moving the ball in the same direction.
Q. What happens if you keep moving the ball in the same direction?
______________________________________________________________________
______________________________________________________________________
7. The bright light represents the sun and the Styrofoam ball represents the
moon. As the moon revolves around Earth we see different amounts of its sun lit
half. This causes the phases of the moon!
Q. Where is the moon in its orbit at:
 a crescent?
________________________________
 first quarter?
________________________________
 full moon?
________________________________
 third quarter?
________________________________
 new moon?
________________________________
Post-activity
Now that you understand more about the phases of the moon how would you answer
the following question:
Why does the moon appear to change shape or go through phases?
______________________________________________________________________
______________________________________________________________________
______________________________________________________________________
______________________________________________________________________
______________________________________________________________________
Credits: Adapted from the Lake Afton Public Observatory http://webs.wichita.edu/lapo/demon.html by the ASU Mars Education
Program (9/06)
Name____________________________________Date_________________________________
Activity 2: Location of the Moon
The position of the moon in our sky at different phases can be demonstrated. The
position of the sun and Earth will first be used to establish directions.
1. Stand facing the sun (bright light).
Q. What time of day does this represent?
________________________________
Q. What direction are they facing?
________________________________
Q. Which direction is to their left?
________________________________
Q. Which direction is to their right?
________________________________
2. Now turn so the sun sets.
Q. In which direction did you have to turn (left to right or right to left)?
___________________________________________
3. Think about what time you see the sun.
Q. What time is it when the sun is directly to their right?
___________________________________________
Q. What time is it when the sun is directly to their left?
___________________________________________
Q. What time is it when the sun is behind them?
___________________________________________
4. Turn so the sun is setting.
Q. What direction are they facing?
____________________________
Q. Left and right are what directions?
____________________________
5. Hold the moon so that it is in the same direction as the sun. This is the new
moon phase since the sun is lighting half of the moon that is facing away from
us. Now move the moon in its orbit (to the left).
Q. What happens?
____________________________
Q. In what direction should they look to see the crescent moon at sunset?
____________________________
6. Move the moon so it is in front of you.
Q. What phase is this?
__________________________
Q. In what direction is the moon?
__________________________
7. Continue until they reach full moon.
Q. In which direction should they look for a full moon?
__________________________
Q. What happens if you move the moon further in its orbit?
__________________________
Q. When should you look for it?
__________________________
8. Repeat the above procedure, except turn so the sun is rising.
Q. What direction are they facing now?
_________________________
Q. What directions are right and left?
_________________________
Q. Where should they put the moon in its orbit so that it is full?
_________________________
9. Slowly move the moon in its orbit.
Q. How does the phase and position change?
_________________________
Q. Why is this different from before?
_________________________
Credits: Adapted from the Lake Afton Public Observatory http://webs.wichita.edu/lapo/demon.html by the ASU Mars Education
Program (9/06)
Phases of the Moon Flip Book
Grades 3-5
Objective
Students will make a flipbook of the moon to see how the phases change.
Materials
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Moon Flipbook Pages
3'' x 5'' (8 cm x 13 cm) file cards (16 per flipbook)
glue
wide clear packing tape
rubber bands
Procedure
Make enough copies of the flipbook pages for each student. Cut these into
sets.
Make up a set of moon phase pictures and file cards for each student. Glue
the #1 picture on the file card of each set as a model for the students. This
should be placed in the lower left corner as shown.
Activity
1. Review the moon phases and how they occur. Tell the students that
they are going to make a flipbook which will be like a movie of the
moon's motion around Earth.
2. Distribute 16 file cards to each student. Show them the model of the
first card so they will know where to glue the rest of the pictures on
each card.
3. After all pictures have been glued on cards, help students lay these in
a pile in numerical order, beginning with card #16.
4. Arrange each set of cards so the lowest edges are slightly offset about
1/4 inch (6 mm) above the card underneath. (See drawing on page
17.) This will enable the thumb to flip rapidly through the cards when
they are stacked.
5. Hold the card stack in place with a rubber band and flip through them
to see if the sun can be seen clearly at the top of the cards and the
moons appear to move around Earth.
6. Remove the rubber band and place a long strip of clear packing tape
along the back of the cards and overlap the front card for about 1 inch
(2.5 cm). This will anchor the cards in place. Run a second strip
vertically around the top of the cards. Be sure to avoid locking the
cards in place so they will not flip easily. If this happens, use scissors
to slide through the tape at the sides until the cards move freely.
Closure
Demonstrate to the students how to hold their books at the top in one hand
and use their thumbs to flip the pages rapidly, creating the motion-picture
effect. Have them do this several times and then discuss the position of sun,
moon, and Earth with them as they flip the pages. They should see the
moon moving around Earth. Now, have them look only at the moon phases
in the lower corner of the cards as they flip the pages. The phases should
rapidly change from new through all the phases and return to the new
position.
Relate this motion of the cards to what they have seen in the sky as well as
when they used their moon balls in the bright light.
National Science Content Standards covered
•
CONTENT STANDARD A: As a result of activities in grades K-4,
all students should develop
– Abilities necessary to do scientific inquiry
– Understanding about scientific inquiry
•
CONTENT STANDARD B: As a result of the activities in grades K4, all students should develop an understanding of:
– Properties of objects and materials
– Position and motion of objects
– Light, heat, electricity, and magnetism
•
CONTENT STANDARD D:
As a result of their activities in grades K-4, all students should
develop an understanding of
– Objects in the sky
– Changes in earth and sky