Tracking Changes in Photoperiod Around the Globe

Background

The Mystery Class project lets students observe first-hand how photoperiod changes around the globe with the advance of spring in the Northern Hemisphere. Photoperiod is the amount of daylight between sunrise and sunset each day.

Every Monday between February 10 and April 21, students will measure their local sunrise and sunset times. Using this information they'll calculate day length in their own hometown. On the same day, students at 10 Mystery Class locations around the world will also record sunrise and sunset data. On Friday of each week, the data from the Mystery Classes will be delivered to your classroom from points around the globe, thanks to Mrs. Berger's fifth graders in Roslyn, New York.

In May, you'll have a chance to guess where the 10 Mystery Classes are hiding! The only clue: As spring sweeps across the Northern Hemisphere, day length changes everywhere on earth.

Here's What You'll Do
1. Every Monday, between February 10 and April 21, record the time the sun rises and sets in your hometown. Your local newspaper should provide this information or you may find it in a calendar from your area.

2. Calculate photoperiod by counting the number of hours and minutes the sun is up. For example, if the sun rises at 6:50 a.m. and sets at 17:30 p.m., the photoperiod for that day is 10 hours and 40 minutes.

3. Record the sunrise and sunset times and the photoperiod for each Monday at your hometown on a datasheet. Then plot the photoperiod of your hometown on a graph. (A Mystery Class graph will also be provided on this WWW site next week.)

Do not send your local sunrise & sunset data to Journey North!

4. Every Friday, Mrs. Berger's students will send you the sunrise and sunset data they've collected from our 10 Mystery classes. Notice: The data you receive on Fridays will have been collected on the same Mondays your readings were collected.

5. Record the data from each Mystery Class site on a separate datasheet and calculate the photoperiod. Then plot the photoperiod from each Mystery Class on your graph. Use a different colored pencil for each Mystery Class.

6. Beginning in March, clues about the geography and culture of each site will be included with the weekly data reports. On May 1st, students will race to guess the location of each Mystery Class.

7. May will be "Meet the Mystery Class Month". Each Mystery Class will introduce themselves on-line and you'll have a chance to correspond with them.... Who ever and where ever they are!