Fill in the blanks using these words. You'll use some words more than once.

During Weeks 1-6:
I started by learning how to use the sunrise/sunset times to calculate the photoperiod at each site. Then I graphed the week-to-week changes in photoperiod at each Mystery Class, and at my own location too.

Locations whose photoperiod increased were in the Northern Hemisphere, while those whose photoperiod decreased were in the Southern. Locations whose photoperiod changed very little were near the equator. A location's north/south position relates to the latitude part of its global address.

I narrowed my search by comparing each location's photoperiod to photoperiod at my home location, which told me if a Mystery Class was north or south of me. After graphing and tracking the Mystery Classes for several weeks, I was also able to put them in order from north to south.

I discovered that I knew a lot about the latitude of the Mystery Classes, but I still didn't know anything about their longitude. This is because tracking the changes in photoperiod does not tell you anything about longitude.

During Week 7:
I finally learned how to estimate the longitude of the Mystery Classes by calculating the amount of time that passed on March 20 between sunrise at Greenwich, England and sunrise at a specific Mystery Class using UT. I then converted that amount of time into minutes, and divided that number by 4 to learn how many degrees away from Greenwich a specific Mystery Class was. Then I looked at the specific Mystery Class's UT sunrise time to see if it was before or after the UT sunrise time at Greenwich, and that told me if it was east or west. This calculation only worked on that date, the vernal equinox.

During Weeks 8 – 11:
I zeroed in on each Mystery Class with clues about their continent, country, province/state and finally city.