Instructional Video

The Leap Second Explained

Everyone's heard of leap years ... but what about leap seconds? Young scientists get acquainted with one of humankind's most awkward standard measurements with a short video from a PBS playlist covering space and time measurement. The resource discusses why leap seconds are occasionally added to our day, the many ways the length of a second has been determined, and how Earth's rotation governs our measurement of time.

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CCSS: Adaptable
Additional Tags
Instructional Ideas
  • Add the video to a time-related lesson plan or to enhance a study of Earth's rotation
  • Have the class research and compare atomic clocks to the standard digital and analog clocks found in most classrooms
Classroom Considerations
  • Pupils should be aware of standard units of measurement and some basic information about how Earth rotates on its axis to better understand the video
  • Despite its complicated nature, the resource presents the content clearly and concisely
  • Illustrations and printed text help viewers connect the various ideas about time measurement in the video
  • None
Common Core