Download Lesson #4: The Moon and its Phases

Earth and Space Science
Lesson #4: The Moon and its Phases
Time Frame: 1 session of 30 minutes
Learning Standards:
The Earth in the Solar System
13) Recognize that the earth is part of a system called the “solar system”
that includes the sun (a star), planets, and many moons. The earth is the third
planet from the sun in our solar system.
15) Describe the changes that occur in the observable shape of the moon
over the course of a month.
Skills of Inquiry:
- Participation as a class in the demonstration
Student will be able to:
Describe, compare, and explain the motions of planets, moons, and comets in
the solar system.
Describe and explain common observations of the day and night skies.
Explain common observations of the day and night sky.
Background Information for Teacher:
Moon Phases Simplified:
It's probably easiest to understand the moon cycle in this order: new moon
and full moon, first quarter and third quarter, and the phases in between.
As shown in the above diagram, the new moon occurs when the moon is
positioned between the earth and sun. The three objects are in approximate
alignment (why "approximate" is explained below). The entire illuminated portion
of the moon is on the backside of the moon, the half that we cannot see.
At a full moon, the earth, moon, and sun are in approximate alignment,
just as the new moon, but the moon is on the opposite side of the earth, so the
entire sunlit part of the moon is facing us. The shadowed portion is entirely
hidden from view.
The first quarter and third quarter moons (both often called a "half moon"),
happen when the moon is at a 90 degree angle with respect to the earth and sun.
So we are seeing exactly half of the moon illuminated and half in shadow.
Once you understand those four key moon phases, the phases between
should be fairly easy to visualize, as the illuminated portion gradually transitions
between them.
An easy way to remember and understand those "between" lunar phase
names is by breaking out and defining 4 words: crescent, gibbous, waxing, and
waning. The word crescent refers to the phases where the moon is less that half
illuminated. The word gibbous refers to phases where the moon is more than half
illuminated. Waxing essentially means "growing" or expanding in illumination,
and waning means "shrinking" or decreasing in illumination.
Thus you can simply combine the two words to create the phase name, as
follows:
After the new moon, the sunlit portion is increasing, but less than half, so it is
waxing crescent. After the first quarter, the sunlit portion is still increasing, but
now it is more than half, so it is waxing gibbous. After the full moon (maximum
illumination), the light continually decreases. So the waning gibbous phase
occurs next. Following the third quarter is the waning crescent, which wanes until
the light is completely gone -- a new moon.
Anticipatory Set: Explain to the students that they will be required to work
together as a class to understand the demonstration of moon phases.
Activity:
1. Turn on the model sun and turn off the other lights in the room. Have your
students stand. Tell them in this system the lamp is the sun and their head is the
earth. Their nose is their hometown on the surface of the earth.
2. Ask your students to stand so that it is noon in their hometown. (Their nose
should point toward the sun.) Have them turn (rotate) until it is midnight in their
hometown. I have my students rotate in a counterclockwise direction to simulate
the direction as seen from the North Pole. (Midnight is when they have their
backs to the sun.) Students can also rotate to show dawn and dusk in their
hometowns and get an idea why the sun appears to rise in the east and set in the
west.
3. Hand out the lunar lollipops (moons) and tell your students that it should be
held at arm's length away from their head. Demonstrate how the moon orbits the
earth in a counterclockwise fashion (from right to left). As students watch their
moon they will see that it will go through phases similar to those of the real moon.
4. Go through the 8 major phases of the moon with your students.
a. New moon - moon is between the sun and the earth and they see the
shadowed side of the moon. A solar eclipse occurs in this phase when the moon
blocks light from the sun from reaching a portion of the earth. Students can close
one eye and simulate this event.
b. Waxing crescent - rotating from a new moon toward a first quarter, backwards
"c" shape will appear on the moon.
c. First quarter - right half of the side of the moon facing earth is lit. The right
shoulder is point towards the sun.
d. Waxing gibbous - rotating from a first quarter to a full moon.
e. Full moon - earth is between the moon and the sun, the entire lit side of the
moon is visible on earth, (students' backs are to the sun and moons are lifted up
to be lit). A lunar eclipse occurs when the moon passes through the earth's
shadow. Have your students simulate this event.
f. Waning gibbous - rotating from a full moon to a last quarter, less and less of
the moon is lit each night
g. last quarter - left half of the side of the moon facing the earth is lit, left shoulder
is pointing to the sun.
h. Waning crescent - rotating from a last quarter to a new moon, a "c" shape of
light is seen on the left side of the moon.
5. Have your students repeat the phases on their own as you circulate through
the room to correct any problems.
Closure: Ask students which moon phases they remember and how often they
have seen these moons. How often is the moon full? Is the moon a star like the
sun? Where is it found in relation to the other parts of the solar system they have
learned about? Have students locate the moon on the classroom solar system
map and remind them to make a sketch of where it is so that they will be
prepared for the next week’s lesson where they will be building their own models
of the solar system.
Assessment: Group participation in moon phase demonstration and class
discussion.
Resources and Materials: Light bulb (suspended from ceiling or on a stand),
Styrofoam balls 2-3 inches in diameter (1 per student), and plenty of room for
your students to rotate in!
Note: Before this lesson you will need to do a little preparation. It is important to
make sure the lights for the "suns" work. Also, either prepare the lunar lollipops
by impaling the balls on a pencil, bamboo skewer or wood splint for a handle (or
have students do this during lesson).