Get Ready for Mystery Class 2020*
  Mystery Class starts January 27, 2020. Get ready this fall by tracking changes in day length as the Earth revolves around the Sun. More...
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Revolving Earth

 

Mystery Class is a global game of hide-and-seek. Follow photoperiod clues to search for ten secret sites around the world. Track sunlight to solve a mystery—and discover the reasons for seasons along the way.

*Please note: Our spring 2020 Mystery Class challenge is a replay of a previous year's challenge. You have open access to all of the season’s clues (Weeks 1-11). We will reveal the locations of the 10 Mystery sites on April 13, 2020.