Mystery Class 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 Back to Teacher Tips Page Facebook Pinterest Twitter © 1997 – 2019 Journey North. All rights reserved.