Time – Teacher Notes
Guiding Questions:
What time is it really?
Why do we need a single, universal time?
How do we keep track of time?
Order:
1. Longitude
2. Measure Your Longitude
3. What Time is it?
Discussion
Activity
Discussion
Explanation:
This unit defines the problem that time as measured by the sun is variable on a time scale of days
and hours. Students are challenged to calculate their longitude, which establishes the necessity of
knowing the time to calculating position on Earth—thus the necessity of keeping accurate track of
a stable, universal time.
In the last discussion, students discuss and learn about how time changes from day to day and
how humans have developed a system for keeping Universal Time.