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Paper Plate Education
"Serving the Universe on a Paper Plate"

Activity: Directions- Terrestrial and Celestial

The following text is excerpted from GLPA Proceedings, 1992, pp. 80-81.  Used with permission:

Introduction to students:

"I wonder how different we would think if we had to write on paper plates instead of rectangular notebook paper."  Pass out two plates per student.  "With notebook paper we are used to thinking of starting at the top, writing toward the right, and continuing to the bottom.  With paper plates we have no top, right, or bottom!  "What do we have to describe the surface?"  Let students offer ideas.  "Everyone fold your paper plate.  Now we have a line with two ends.  Write an 'N' on one end (doesn't matter which end).  "End sounds line 'N', but 'N' might also stand for 'north'.  So write 'S' on the other end of the line for 'south'."

"Fold your plate so the 'N' edge meets the 'S' edge.  Unfold the plate.  Now we have a new line.  Hold the plate so 'N' is up and 'S' is down. 

"Let's use the tool you have made to find out which direction the sun is right now.  Take your paper plate outside on a sunny day.  Mark around the edge with the cardinal directions.  Put it on the ground or a table or a book so 'N' on the plate is pointing north."  [Help students get started by knowing something on the horizon north of the school...a tree, grain elevator, house, etc.]  "Place your pencil point on the center of the plate.  Lean the pencil until the shadow is the shortest you can make it.  It helps to make a small hole in the center of the plate to hold the pencil point, and tie two strings around the pencil so your finger shadows don't get in the way.  If you stand over the plate looking down (work in pairs) you can see which way the sun is from your location.  Draw a line where the shadow is and put down the time.  Repeat this during the day until you can predict correctly where the shadow will point at each time of the day.  If you make the length of the shadow when it is the shortest, record the date and do it again over several weeks, you will see a pattern of the sun's position at different times of the year."  It would be neat to do this for stars and the moon, but the moon shadow is more difficult to see and the stars light is too dim to cast much of a shadow, so we need a 'celestial paper plate'.

Terrestrial vs. Celestial Paper plates.

To make a celestial paper plate, transfer the directions from the terrestrial over the edge to the other side all around the plate.  When you look down at the back side it looks like you went around the plate the wrong direction!  But hold it over your head and now when you point 'N' to the north, 'E' is once again pointing east instead of west.  Now we use the plate at night.  Holding the plate overhead with 'N' pointing north, draw the bright stars you see and the moon if it is in the sky.  If you don't like working on your back, stand up, fold the plate in half and face north.  Make the fold line the horizon and draw the bright stars you see in the north part.  Face south and use the other half of the plate to draw what you see in the south sky.  Turn the plate over or use another plate and do the east and west sky.  Then go to a star chart in a book and try to figure out which stars you were seeing.  Be sure you mark the date and time on your paper plate 'star chart'.

Contributed by Wayne James.

 

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