Teacher's Guide for:

Reasons for the Seasons

Objectives: 

This show conforms to the following state science standards:  12.F.1b, 12.F.2a, 12.F.2b, 12.F.2c

Brief Show Summary:
The show is presented in three major parts: 
1) students predict and then watch the sunset position on the current date and then observe and record the changing sunrise and sunset positions at the equinox and solstices.  We also can count the number of hours of daylight for each of these times. 
2) We then examine how the changing altitude of the Sun affects the weather. 
3) Students then explore the reason (axial tilt) for these changes using an Earth globe.  If you wish, you can print and duplicate this sheet and bring the copies with you to your reserved time.  Be sure each student has a pencil and a book of some sort to write on. 

Pre-visit Discussion & Activities: 
1) Ask the class why it is cold in the winter.  The most common misconception is that the Earth is farther from the Sun.  Ask how they know that and how could we find out. 
2) Use a diagram of the Earth's orbit about the Sun to briefly discuss the seasons.   Misconceptions can result from drawing the Earth's orbit as an oval, implying that maybe  we are closer to the Sun in the summer.  The Earth's orbit is almost a perfect circle as  viewed from above.
3) Begin charting the seasons by 
     a) instructing students to watch the position on the  horizon of the sunset or 
     b) measuring the length of a shadow at noon, or 
     c) recording the  number of hours of daylight each day. 
4) Establish the idea that the Earth rotates by closely watching the shadow of a stick.   Why does the shadow move? 

Post-visit Discussion & Activities:
1) Discuss with the class what the effects would be if the Earth's axis were not tilted 23.5  degrees.  What if it were zero degrees?  What if it were 90 degrees?  This is the case for  Jupiter and Uranus respectively. 
2) Use a globe and a light source as was done in the planetarium to discuss the situation  at both poles.  How much daylight do they receive at the equinoxes and solstice?  You  can also use the globe with a short pencil taped on Central Illinois coming straight out of  the glove to show how shadows will appear different lengths depending on the season. 
3) Shine a regular flashlight on a table at roughly a 70-degree angle and have students  describe the spot they see.  If the flashlight is mounted somehow, they may even measure  its long and short diameters.  Then move the light source until the light rays are striking 
the table at roughly a 25-degree angle.  Does the spot change?  How?  How is this related  to our seasons?

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