Real World Math: Around the World in 40 Hours

In this activity students will take part in a series of consecutive plane trips around the world while keeping track of the time for each time zone they land in. 

This could be considered Part 2 of RWM’s Time Zone Problems lesson in which students convert time from time zone to another.  The major difference between the two is that in this activity the students add on elapsed time and then calculate the local time for each airport they land at.

Anyone who has taken an airplane flight across time zones has experienced this real world math problem.  Imagine trying to reset your watch if you travelled completely around the world.  In the scenario presented to students, Phil Fogg starts his trip in Honolulu and attempts his circumnavigation in 40 hours using commercial airliners. After stops in Tokyo, Paris, and other cities he returns back to Honolulu.

These exercises are quite confusing.  In addition to converting time between time zones, the students must also add on the time for each flight from airport to the next.  A solid understanding of regrouping with units of time is needed for this, as some flights pass from one date to the next.  To simplify matters, daylight savings time is not considered nor are the layover times at each airport.

The Google Earth Kmz file for this lesson is the same as the Time Zone Problems lesson.  You may wish to refer back to that lesson and review some of the skills discussed, including the time zone conversion formula (see below).  Students should have an easier time performing these problems if they use 24 Hour clock times.  Be sure to point out that time is not a base 10 system but rather base 60 for minutes and base 24 for hours.  I’ve included a travel log with the downloads below.  I would recommend treating this as a passport to stamp as students successfully calculate each landing time.  You’ll want to keep track of their work because once they make an error it will continue for the remainder of the exercises.

Finally, I considered having two routes for this lesson: one westward and the other eastward.  Perhaps I’ll add that in the future.  As always, you are encouraged to adapt this lesson as you wish.  Feel free to add stops or change the route.

The conversion formula relies on the knowledge of what time zone each site is located.  This is easily found in the Google Earth download in the form of icons that circle the globe.  Clicking on one of these icons will display the offset value from Coordinated Universal Time (UTC).  Since the time in zone A – the UTC offset value of zone A = time in zone B – the UTC offset value of zone B the following formula can be used…

time in zone A = time in zone B – UTC offset of zone B + UTC offset of zone A
This is truly a real world math topic that is worth exploring with students.  One avenue to pursue would be the history of recording time and how it has changed.  Another topic of discussion would be the irregularity of the time zone boundaries – “why don’t these follow lines of longitude?” or “what longitude value would the zones be if they were regular?”  Finally, you might want students to imagine changes that might take place in the future and the reasons for them.


  • Calculate elapsed time
  • Calculate time from one time zone to another
  • Use a formula to calculate differences in time zone

Student Worksheet
Student Travel Log
Teacher Key

Measurement & Time
K-6, Middle School, Educator

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