Inquiry 2.1 (Investigating Lunar Phases)
Purpose: What causes people on Earth to see the moon going through the different 8 moon phases?
Background Information:
• What is an orbital plane?
• What are moon phases?
• Does the moon give off or reflect light?
• What is illumination?
Hypothesis: IF you see the illuminated side of the moon __________________________, THEN
you will see the different moon phases.
Procedures:
A. Look at the picture to the right of the materials
you will have for this inquiry. How can you use
the Sun-Earth-Moon (SEM) Board and a flashlight
to investigate how much of the Moon is
illuminated (lit up) by the Sun at any one time as
the Moon revolves around the Earth? Discuss your
ideas with your group. Write down your thoughts
and show me your group’s idea (#1).
B. After I approve your idea, get your SEM board from your lab station.
C. Push the smaller sphere onto rod #1 through the predrilled hole. This sphere will represent the
Moon in its orbit around Earth.
D. Look at the image to the right. What do you notice
about the Moon’s orbital plane (RED CIRCLE),
compared to the Earth and Suns? Discuss your
ideas with your group and then write down your
answer (#2).
E. Now compare the picture above to your SEM
Board. (#3a)What do you think the rods on your board represent? (#3b)Why are the rods different
heights? (#3c) Why does the rod go through the globe at an angle? Discuss and write down your
answers. Show me your answers to receive the 2.1worksheet.
F. Shine the flashlight directly on the sphere on rod #1. Keep the flashlight steady. Look at the
sphere from all directions as if you are looking down at the Moon from space above (bird’s eye
view). How much of the sphere reflects light at any one time? Discuss your observations with
your group. Color circle #1 on the worksheet 2.1 to show how much of the Moon is dark and how
much of it reflects light. Make sure that the worksheet is facing the same direction as your SEM
Board.
G. Move the sphere to rod #2. Shine the flashlight directly on your white sphere
as you did with rod #1 (see the picture to the right, the flashlight should
ALWAYS be on the side that is labeled SUN with tape because the Sun does
not move). Discuss your observations with your group. Record what you see
in circle #2 on worksheet 2.1.
H. Repeat Step G with the other rods (#3–#8). Record your observations on
worksheet 2.1 after each time.
Analyzing the Data
Answer the following questions after discussing them with your group and put
part of the question into the answer.
4a) As seen from space, how much of the moon is always illuminated (lit up)
by the Sun?
4b) Given your results from this inquiry, why do you think the Moon appears to change its shape
(moon phases) when viewed from Earth? (This is your best guess!)
I. Cut along the perimeter of the circle by cutting through each of the moons.
J. Glue your circle onto your notebook paper and create the data table below.
K. Complete the first column below for the amount of the lit side of the Moon that you can see
(from the Earth) using your 2.1 worksheet. Choose one of the following answers:
All or more than half or exactly half or less than half or none.
(You will complete the Moon Phase column after inquiry Part II…NOT NOW.)
Moon Position
1
2
3
4
5
6
7
8
Illuminated Amount of moon
Moon Phase
Don’t fill in this column now!
You…
Will…
Complete…
This
AFTER
Part
II
d) What pattern do you notice when moving from position 1 up to 5?
e) What pattern do you notice is taking place from positions 5 up to 8?
f) What pattern do you notice in the data table from position 1 all the way around to position 8?
Show me your work when your group has completed the analyzing the data questions and then
I will hand you the Part II worksheet.
Part II - Modeling Lunar Phases
A. Remove the globe of the Earth from the blue peg on the SEM board.
B. Put the Moon back at position #1 on the SEM board. Shine the flashlight at the Moon again like
you did for inquiry 2.1, holding the flashlight on the side labeled Sun.
C. With one group member holding the flashlight, the other group members should look at the moon
from the opposite side of the SEM board (looking from behind position #5 at the moon). Make
sure your head is level with the moon (you will have to squat down to do this).
D. Observe how much of the Moon is lit up by the flashlight (Sun) at this angle. Using the outside
circle on worksheet 2.2 (beginning with position #1) showing how much of the Moon is
illuminated (lit up). Make sure the worksheet’s Sunlight side is the same side as your flashlight /
SEM board.
E. Move the Moon to position #2 on the SEM board and shine the flashlight on the Moon. Make
sure you keep the flashlight on the side labeled Sun and the light directed at the moon.
F. With one group member holding the flashlight, the other group members should look at the moon
from the opposite side of the SEM board (looking from behind position #6 at the moon). Make
sure you are viewing the moon at eye level.
G. Observe how much of the Moon is lit up by the flashlight (Sun) at this angle. Shade in the
outside circle on worksheet 2.2 for position #2 showing how much of the Moon is illuminated (lit
up).
H. Continue this procedure for the remaining positions. Remember to always look from the opposite
side of the SEM board and have the worksheet the same way the SEM board is positioned.
I. Put the Earth back on the center peg and return the SEM board and get the 2 large Styrofoam
Moons from me.
Part III Modeling the Moon Phases
A. Place the large black-and-white sphere on the end of a pencil. This will represent the Moon.
B. Face the Sun on the overhead. Hold the Moon out in
front of you so that the white half of the Moon is
facing the Sun, as shown in the picture. How much
of the white part of the moon can you see?
C. Orbit the Moon around you. Stop when your back is
facing the Sun. The white part of the Moon will
ALWAYS be facing the Sun (your head will
represent the Earth). Does the white part of the moon
appear to be growing larger or smaller?
D. Now continue to turn while looking at the moon until
you are facing the Sun again. Did the white part of
the moon appear to be getting larger or smaller?
E. Compare your observations of this moon phase to the
answers you drew on worksheet #2. Make sure that
the Sun on your worksheet is facing the same
direction as the Sun on the screen.
F. Switch roles within your group. Have another student
hold the Moon, and repeat Steps 2–4. Do this until
everyone has had a turn to observe all 8 positions.
G. Get and read “How Moon Phases Work” from my website.
Analyzing Data
Directions: After discussing the following questions in your group, answer the following questions
on your notebook paper. Make sure to put part of the question into your answer.
1. As seen from Earth, what causes the Moon to change its apparent shape throughout the month?
2. Approximately how long does it take for the Moon to go through all of its phases (from New
Moon to New Moon)?
3. Is the moon only visible in the nighttime sky? Explain why or why not. Hint: Think about
what you saw when you were facing the Sun (which represented daytime on the Earth).
4. Does everyone on Earth see the same phases of the Moon on any given day? Explain why or
why not?
5. Is the same side of the Moon always dark? Explain why or why not.
6. Go back to your data table and label each of the moon phases. Now answer this question What patterns do you see of the illuminated side of the moon (use your data table)?
** Show me your group’s answers to the Analyzing the Data questions before
beginning the Lunar Phases Interactive Activities.
Conclusion
• Restate your entire hypothesis.
• Explain why your hypothesis was correct or incorrect.
• How much of the moon is always illuminated by the Sun?
• What are the main reasons we see different moon phases?
• Explain why Earth does not see any of the moon illuminated during a New Moon phase.
• Describe the pattern the moon phases go through from New Moon to New Moon.