UNDERSTANDING THE PHASES OF THE MOON

                   (a three part project)

OBJECTIVE:  The objective of this project is to understand   
            why on earth, we see the moon in phases.  It
            is meant to follow an earlier project, 
            Multiple Sides of the Moon.  

OVERVIEW:   This project can be broken down into three       
            parts.  During the first part, students will
            develop an understanding of why the moon has
            phases.  During the second part, students will
            observe these phases.  Finally, students will
            test their knowledge of the phases in a fun
            and non-threatening manner.

                          PART ONE

QUESTION:  Why does the moon appear to us, on earth, in
           phases?

ANSWER:    The phases of the moon change as the angle made   
           by lines from the sun to the moon to the earth
           varies.  As this angle change occurs, the         
           fraction of the moons illuminated side visible
           from earth changes.  This is illustrated below.

EXAMPLE:   During the day, take an orange outside.  Look for
           the moon in the sky. (Yes, you can see the moon
           during daylight hours.)  Hold the orange in your
           hand and extend your arm.  Now align the orange 
           and the moon.  Notice that the illumination on
           the orange matches the illumination on the moon.
           What happens to the orange if you move it in an
           East to West direction?  What does this simulate?

                          PART TWO

PURPOSE:   The purpose of this section is to observe and
           record the changing phases of the moon.

MATERIALS: You will need a calendar, drawing paper, pencils,
           28 days to complete the project and participants.

PROCEDURE: Assign a student to each day of a 28 day period.
           When a student's day comes, they are to
           observe the moon in the evening.  That student
           will sketch the moon and record the date, local
           time, and location of the moon with respect to
           the horizon and meridian.  Arrange these drawings
           in chronological order on the calendar.

  TO
PROCESS:   Where your findings in correlation with what
           you expected to find?  Did the moon complete
           a cycle within the 28 day period?  How did the 
           moon's position in the sky vary?  Why?


                         PART THREE

PURPOSE:   You are going to test you knowledge of the
           moon's phases.

MATERIALS: Light source, a picture of each phase of the
           moon, a small ball to go with each picture.

PROCEDURE: One person volunteer to represent earth, and
           stand in the path of the light source.  Other
           students make pairs so that their is one pair
           for each phase of the moon.  One person in the
           pair hold their picture of a phase, and the 
           other hold the ball.  Now, each pair station
           themselves in a position on the circumference of
           a circle around the "earth" that represents the
           position the moon would be in during it's orbit
           if it was illuminated as in your picture.  The
           earth will then check the illumination of the 
           ball.  If a pair is in the correct position, it
           will match the illumination in the picture.

  TO
PROCESS:   What about eclipses?  What are possible
           misconceptions that could arise?  What
           knowledge did you need to complete this
           project?  How could you improve this
           project?