Exploring Universal Time

During the Mystery Class Seasons Challenge, students will use Universal Time clues to estimate the longitude of secret locations. Use these resources to help students build key concepts and make connections.


Local Time is the time people see on their clocks. Local time is based on the sun's day/night cycle in each of the world's 24 different time zones.

Universal Time (UT) is a measure of world time. It is based on the local time at the Prime Meridian in Greenwich, England (at zero degrees longitude). Universal Time and Greenwich Mean Time (GMT) can be used interchangeably. Universal Time is an international time-keeping standard. We use it to communicate about events that occur at a specific moment. In Universal Time, it is the same time everywhere on Earth.

Lessons and Activities
Follow the Sun Time Zones Map activity Follow the Sun
World Clocks Time Zone Riddles When's Your Birthday?
Follow the Sun What makes Day and Night? Prime Meridian
Eating on the Equinox Day and Night East and West