Labs from YSI 94 :
Our Sky Clock.

April Whitt
CARA Yerkes Summer Institute, August 1994

This is a Teacher's Guide.

Students identify events as regular (such as the seasons, most holidays and moon phases) or as irregular (such as weather and the varying rates of heartbeat and breathing). Observations of two star patterns in the nighttime sky show some regular, repetitive events that can be used to "tell time." Earth's motion appears to make the "Big Dipper" rotate around the North Star approximately once every 24 hours. Students construct "sky clocks" using the Dippers and Polaris to discover how they can tell time by observing stars in the nighttime sky.


Students will:

Materials Needed

Paper fasteners, worksheet, crayons, scissors


Overhead: Worksheet transparencies
Slides: "Big Dipper" and "Little Dipper" ("Bear")


  1. Discuss, with models and student volunteers, if possible:
  2. Discuss constellations
  3. We can use the stars
  4. Construct star clocks
  5. Demonstration of use
Important Disclaimers and Caveats: