Paper Plate Education
Activity: Gno Problem Mon
The following text is reprinted from GLPA Proceedings, 1993, p. 35. It was written by Jeanne Bishop as part of a series of in-planetarium lesson plans. Used with permission.
SUNDIAL: Foam plate,
scissors, printed circular protractor (angles of azimuth are measured), tape
nail, plastic straw, marker, a very bright light (I clamped one to a ringstand
on a cart and wheeled across one end of the room).
Cut out the "angle dial."
Tape it to the bottom of the foam plate (dial is elevated).
Punch a hole at the center of the dial.
Wiggle the nail to make the hole just large enough to hold a straw.
Mark the straw upright. Mark
north where the 0 is on the dial. Mark
east where 90 is on the dial. Mark
south where 180 is on the dial. Mark
west where 270 is on the dial. ''When
I turn on this light, my pretend-sun, do you think you will see a shadow? If I
keep the "sun" here, how could a shadow fall across my dial?
(Student answers) Turn on
the light and note how the shadows point away from it. Move the light-sun across an arc at the south end of
the room, changing its height to greater angles by sliding the light higher on
the ringstand. Students watch what
happens to the direction and height of their shadows.
Write the name "Gnomon" on the board and define it.
Discuss sundials the students may have seen.
(Some realized that the gnomon was tipped and I invited them to tip their
straws in the north direction. I
moved the light-sun through the same arc.) Straws may be reinforced with tape.
"Take your dial home and watch how the shadow changes with the real
sun in the day. Put it in the
same spot each time you use it, and face it in the correct earth directions.
If you use it now and then again in December, do you think the directions
of the shadows at sunrise and sunset will be the same? Do you think the length
of the gnomon shadow will be the same? Try it!"
Contributed by Jeanne Bishop.
GLPA Proceedings, "Sundial", 1993, p. 35.
Also see GLPA Proceedings, 1992, p. 81, by Wayne James.
Copyright ©2012 Chuck Bueter. All rights reserved.