When I taught astronomy, I found that many students could NOT
understand the diagrams in the book. They saw ovals on the page as ovals,
and not circular orbits tilted out of the plane of the paper. They just
couldn't interpret the book illustrations. Besides, it's hard to understand
this when looking at a static page. There are some astonomy Java applets on
the Web, as well as planetarium software, that let students play around with
animations. These work somewhat better than static diagrams, but students
still can't "see" the concept until they work with 3-D models. Small light
bulbs (even battery-operated) and globe pencil sharpeners work well. The
globe pencil sharpeners even come with the little 23 degree gimbal mount.
The students really didn't start to "get it" until moving the pencil
sharpeners around the light, keeping the axis of the globe pointed at the
same wall of the room the whole time.
Understanding the seasons is HARD. It requires 3-D visualization,
which many people don't have. It requires overcoming some perfectly
reasonable and long-standing misconceptions, which most people DO have.
After all, anybody with eyes can *see* from the picture in the book that the
north end of the earth is closer to the Sun in the summer! If you want to
get warm, everyone knows that you have to move closer to the fire! So it's
*obvious* that the north end is warmer when it's pointed toward the Sun.
It might help to take your globe pencil sharpener and a beach ball,
figure out how far apart they should be according to the scale of the solar
system (based on the globe), set 'em up outside, and THEN point the axis of
the globe toward or away from the "Sun". NOW the students can see that the
distance thing makes no difference. What's missing from the standard
explanations is perspective.
Vickie Frohne
-----Original Message-----
From: Larry Smith [mailto:larry.smith@SNOW.EDU]
Sent: Friday, September 19, 2003 1:33 PM
To: PHYS-L@lists.nau.edu
Subject: Re: Private Universe and the Seasons
I agree bc and find this whole thread interesting, but it begs the question
"What _should_ the diagrams look like?" We can't relly make them to scale
and do any better. Can someone Adobe Illustrator some _ideal_ diagrams for
teaching the seasons and send them all to us as .pdf's? Or are ideal
diagrams impossible? What should we settle on? I don't like the thought
of avoiding diagrams entirely.