NASA
Nasa: Image Science Center: Ask the Space Scientist Earth
Site from NASA contains a collection of 91 questions pertaining to the Earth's atmosphere, magnetic field, ionosphere, rotation and origin of life.
University of Wisconsin
University of Wisconsin: Reasons for the Seasons
A brief explanation of the Earth's rotation around the Sun and how it relates to the amount of sunlight the Earth receives, and to the seasons. Includes two questions for students to respond to.