Tracking Changes in Photoperiod Around the Globe

Mystery Class Update: February 14, 1997

From the bottom of our hearts, thanks goes to Mrs. Berger's class , for providing this Valentine's Day set of sunrise/sunset data from our Mystery sites around the world. Her class REALLY gets around!

Remember, this information was recorded on Monday, the same day you collected your sunrise/sunset data. Don't forget to get up every Monday at sunrise! (Or find your local sunrise/sunset data from your newspaper.)

Here are this week's data:

Journey North Mystery Class
Sunrise/Sunset Data

Data For: Monday, February 10, 1997

* Mystery Class #6 reported 00:00 for their times because, right now, "the sun always shines!"

How To Organize Your Class

1. Divide Your Class into Eleven Groups
Give each group responsibility for one of the ten Mystery Classes, and give one additional group responsibility for your own site. Every week, each group can record the data and calculate the photoperiod for their site. Then, each group can share their calculations with the rest of the class. Each individual student can add the information to his or her own graph.

2. Give Each Group:

• One copy of the Mystery Class Data Sheet , to record sunrise/sunset times for each site.
• Two copies of the Mystery Class Graph , to plot photoperiod at the Mystery Class sites. (See below.)

3. Establish the Scale for Your Mystery Class Graph

VERY IMPORTANT:
In order for your graph to have enough room for a clear picture of the data, we strongly recommend that your graph be tall enough to prevent overcrowding! Use two copies of the Mystery Class graph (or two pieces of 8 1/2 x 11 graph paper) to allow at least an inch per day-length hour. (If you have a Journey North manual, you will need to make 2 copies of the graph on page 100. We apologize for this change!)

A. Vertical Axis
Tape 2 graphs together, so the resulting graph is 22" tall. The left edge of your graph (the 11" side, which is the vertical axis) will indicate day length hours. Allow space for 20 day-length hours in total. At the lower left, begin with 4 hours of day length. Go up the vertical axis to 24 hours, and allow 4 squares for each hour.

B. Horizontal Axis
The bottom of your graph (the 8 1/2 inch side, which is the horizontal axis), will denote the dates of your Monday readings. Mark 11 weeks along the bottom, allowing three squares per week. Write the following dates for your Monday readings along the bottom of the graph:

Feb. 10, 17, 24

Mar. 3, 10, 17, 24, 31

Apr. 7, 14, 21

Try This!
We recommend the example of Wisconsin Third Grade teacher, Cathie Plaehn. Her class creates a huge 3 x 3 wall graph using butcher-block paper to plot the mystery! Each student-group makes their own individual graphs, and the entire class plots data on the wall graph.

The Next Mystery Class Update Will be Posted on February 21, 1997.