From an Astronomy point-of-view, teaching what causes the seasons is an important teacher goal.
I always found at least half of each class still held on to the thought that we are closer to the sun in the summer and farther away in the winter. Once they understand it's the angle of sunlight and that we are closer in the winter, kick it up a notch by having them go home and check out what their parents think!
My most favorite unit I've always called the "Skittles Lesson" because Skittles candies are used as units of heat. My students seemed to stay focused for the most part, especially since they knew they got to eat the candy when they had completed the worksheet!
Since it's such a complicated lesson (the first time), I've written a "How to Teach" handout so you can see what worked for me in getting across this concept.
CONSIDER THIS: Teach the Seasons using Skittles!
Click here for the Skittles Activity, the directions, and also a couple of other active learning activities for teaching "Reasons for the Seasons."
FUN LINKS: Tons of other kewl ideas!
The Perfect Animation for the Skittles Activity: Click here!