Paper Plate Education
Activity: Paper Moons II
The following text was excerpted from GLPA Proceedings, 1993, p. 79; used with permission:
A "Hands-on" experience using 2 common materials(1) Paper
plate (2) Football field. The experience addresses a common misconception about the
motion of the moonthat the moon "loops" around the earthwhen in
fact the path of the moon is always concave to the sun!
At a distance of 100 ydsgoal line to goal line--the plate is about the
radius of the moon's orbit, and the width of the field represents about 30o or 1 month.
The Paper Plate meets the Football Field
or How the Moon Really Moves!!
1. Have students draw a line representing
the motion of the Earth during a time period of 30 days. (Should be an arc
similar to 1/12 of a circle.)
2. Have students draw a line representing
the motion of the moon during that same period. (Note: If the arcs look similar
then there is no need for this lesson!)
3. Most students will make a loop for the
moon around the earth during the 30 day period. The misconception is due to
out-of-scale drawings textbooks use. To
improve students' understanding, make a scale model of the motion.
4. Take students to a local football
field. At the center of one goal
line place a basketball to represent the Sun.
At the other goal line lay a string for the path of the Earth.
The ends of the arc should be about 3 yds from the goal line.
5. Take a cheap, handy, 9" paper
plate. It is best if each student
has one and does the exercise for Hands-On learning. Have the student draw a heavy dot, smaller than the letter
'O' on one side of the plate, and across from it place a small dot (1/4 the size
of the big dot). The big one is to
represent the Earth and the small one the moon. Keeping the Earth dot on the
string, move it along making the moon dot "go around the earth" one
time as you cross the football field.
6. Have each student make a drawing of
what they have traced on the ground onto a notebook size paper for evaluation .
Extension: Start everyone with the moon
toward the Sun and have them mark the phase or draw what the moon will look like
at different points across the football field.
Extension: Give students the data and have
them construct their own model to scale. Find the slight errors in the model
described. Talk about 5 degrees
above or below the surface of the field. CAUTION:
Do not have the students dig up the field to show this!! Coaches do have more
power than science teachers!!!
Extension: Expand the model by making the
paper plate the Earth, cut out another plate for the moon, figure out how far
away the sun would be at this scale, and do the orbital motion across the long
part of the field from goal line to goal line.
HINT: About 33 plate diameters to the moon, 400 times that to the Sun
Extension: Barycenter will be a little
over 1/3 the way from the edge of the plate to the center of the plate.
It is the point that orbits the Sun, with the moon and rest of the earth
swinging around the barycenter.
The Astronomical Companion
by Guy Ottewell.
Contributed by Wayne James.
Copyright ©2012 Chuck Bueter. All rights reserved.