Tip for Calculating Photoperiods

Teacher Jo Leland of Kingwood, TX submitted the chart below, which she uses to aid students calculating photoperiod. Jo has her students break down the calculation first into whole hours, and then into minutes.

Jo Leland
Hidden Hollow Elementary
Kingwood, TX

Calculating Photoperiods--A Way to Doublecheck

Step One-- WHOLE HOURS:
Students first calculate the number of whole HOURS in the photoperiod. They start by writing down the sunrise time, and then the time that is one hour later. They do this for each of the whole hours that follows from the sunrise time to sunset time. Here's an example:

Sunrise 7:17
Sunset 19:04

• 07:17 to 08:17 = 1 hour
• 08:17 to 09:17 = 2 hours
• 09:17 to 10:17 = 3 hours
• 10:17 to 11:17 = 4 hours
• 11:17 to 12:17 = 5 hours
• 12:17 to 13:17 = 6 hours
• 13:17 to 14:17 = 7 hours
• 14:17 to 15:17 = 8 hours
• 15:17 to 16:17 = 9 hours
• 16:17 to 17:17 = 10 hours
• 17:17 to 18:17 = 11 hours
 Total Whole Hours = 11 HOURS

Step Two--MINUTES
After counting the whole hours, the next step is calculate the remaining minutes between the end of the last whole hour and the sunset time:
• 18: 17 to 19:04
 Total Remaining Minutes = 47 MINUTES

 Total Photoperiod = 11 HOURS, 47 MINUTES

If you have tips you'd like to share, please write to Journey North: jnorth@learner.org