The equinox is coming! Notice how the line between light and dark on the equinoxes matches longitude.

Only on the equinoxes do locations at the same longitude experience sunrise at the same time. Next week's Time Clues will help you estimate the longitude of the Mystery sites.

Looking for a Clue?
When sunrise occurs at the Prime Meridian on the equinox, six Mystery sites will already have had sunrise and the other four will still be waiting.

Photoperiod Clues from the Mystery Sites

• Clues for Monday, March 4
• All Spring 2019 Clues
• Record and Graph

Compare Your Photoperiod

• Look up your sunrise/sunset data for March 4.
• Record and Graph
• Guiding Questions

Student Activity
Try this activity to help students make connections between time and longitude.

• Time Clues and Longitude

Teacher Planning Packet
Includes background information that will help you understand the science and math behind time clues.

• Discovering Time Clues

Journal: Predicting Photoperiod

Draw your photoperiod graph the way you predict it will look at the end of March.

• Week #6