Grade Level
5–8

National Standards Addressed
Grades 5–8:
Earth and Space Science: Earth in the Solar System
Science as Inquiry: Design & Conduct Investigation, Analyze & Interpret Data, Develop Explanations, Think Critically

Key Concepts
Seasons, rotation of the earth, earth's axis, day and night, earth's orbit around the sun.

Background Science
Seasons of the year
http://www-istp.gsfc.nasa.gov/stargaze/Sseason.htm

What causes the seasons?
http://www.crh.noaa.gov/fsd/astro/season.htm

Earth's seasons (narrated animation)
http://kids.msfc.nasa.gov/earth/seasons/EarthSeasons.asp

BBC Science and Nature: The Seasons
http://www.bbc.co.uk/science/space/solarsystem/earth/solsticescience.shtml

Ideas for Discussion
• The sun dagger petroglyph was a way for the Chacoans to know when the seasons were changing. Why would this be important for them?

• How do you know when the seasons are changing? Do you use signs that the Chacoans may have used? What modern signs tell you that the seasons are changing?

• How does the change of the seasons affect you?

Related Media
• Our Seasons has a description of how sunlight is affected by the earth's tilt and orbit.

• See an animation showing how the sun moves across the horizon throughout the year (requires the Flash Plugin ).

• See an animation showing how the area of the globe that is in sunlight changes throughout the year (requires the Flash Plugin ).

• What Time Is It on Mars?
A Webcast exploring time and seasons on the Red Planet (requires Real Player ).

Going Further
• Revisit the year stations. Notice the angle at which the sun strikes your dot during the summer versus during the winter. In which season are you the most likely to get sunburned? Why?

• Imagine you are living on the equator. How would you describe the change of seasons?

• Now imagine that you are at the North Pole in the summer. What path does the sun take across the sky?

Check for Understanding
• What special aspect of the sun's position or movement do we mark with the solstices and the equinoxes?

• What would seasons on the earth be like if the axis weren't tilted?