Days are getting shorter in the Northern Hemisphere as winter approaches. Begin to explore the question: What makes seasons?

Mystery Class begins January 31, 2014
Next Countdown: December 1, 2013

What makes seasons?
Image: The Living Earth®

Photoperiod is a central clue in Mystery Class. Build skills by reporting your photoperiod each month.

Report to the Map!

1. Report for November 1

2. Find your sunrise/sunset: Look-up

3. Calculate your day length (photoperiod).

4. Report your day length: Select "Daylight"

Map	Dates to Report	Guiding Questions for Map Analysis

Observe, Wonder, and Predict
Observe images of the Earth from space. See how sunlight strikes the Earth over the course of a year. Use the slideshow and activities to explore the 12-month cycle of changes.

• Slideshow: What Makes Seasons?