ANSWER KEY ® The Savvy Cyber Teacher Using the Internet Effectively in the K12 Classroom Handout #1: Reading the Time/Date Stamp Determining your time and date from a Time/Date Stamp may appear complicated but will become easier with practice. This handout contains several reference charts as well as a few Time/Date conversion examples and exercises. The answers to the exercise can be located on the Week Four Savvy Cyber Teacher® web site (http://www.k12science.org/cyberteacher/). If you have any questions or need assistance, you should contact or e-mail your workshop leader. Conversion Tables Converting Time from a 24-Hour Clock to a 12-Hour Clock 24-Hour Clock 12-Hour Clock 24-Hour Clock 12-Hour Clock 00:00 12:00 midnight 12:00 12:00 pm noon 01:00 1:00 am 13:00 1:00 pm 02:00 2:00 am 14:00 2:00 pm 03:00 3:00 am 15:00 3:00 pm 04:00 4:00 am 16:00 4:00 pm 05:00 5:00 am 17:00 5:00 pm 06:00 6:00 am 18:00 6:00 pm 07:00 7:00 am 19:00 7:00 pm 08:00 8:00 am 20:00 8:00 pm 09:00 9:00 am 21:00 9:00 pm 10:00 10:00 am 22:00 10:00 pm 11:00 11:00 am 23:00 11:00 pm 24:00 12:00 pm Converting Coordinated Universal Time (UTC) to your Local Time Zone Standard Time Daylight Savings Time UTC – 5 hours = EST UTC – 4 hours = EDT UTC – 6 hours = CST UTC – 5 hours = CDT UTC – 7 hours = MST UTC – 6 hours = MDT UTC – 8 hours = PST UTC – 7 hours = PDT Copyright © 2001 Stevens Institute of Technology, CIESE, All Rights Reserved. Version 2.1 ANSWER KEY Related Issues • Time Zones Acronyms: It is important to remember to add or subtract an hour if it is Daylight Saving Time (Hawaii and parts of Arizona and Indiana do not use daylight saving time). Here are the acronyms referred to above. Standard Time Daylight Saving Time EST - Eastern Standard Time EDT - Eastern Daylight Time CST - Central Standard Time CDT - Central Daylight Time MST - Mountain Standard Time MDT - Mountain Daylight Time PST - Pacific Standard Time PDT - Pacific Daylight Time • Time Zone Names: Coordinated Universal Time (UTC) is often expressed in three different ways: Greenwich Mean Time (GMT), Zulu (Z, this is also the American military time standard), and Universal Time (UT). In reality, all of these refer to slightly different time zones that differ only by a few seconds. For our purposes, they all refer to the same time zone. Time/Date Stamp Conversion Examples The following are two examples that illustrate how to read a Time/Date Stamp and how to determine the age of the data. Example 1: Time/Date Stamp: 12 DEC 00 07:00 UTC Current Time: December 12, 2000 8:00 am Location: Miami, FL 12 DEC 00 = December 12, 2000 UTC – 5 hours = EST 07:00 UTC – 5 hours = 02:00 EST 02:00 UTC = 2:00 am EST, therefore . Time and Date the data was recorded: 2:00 am December 12, 2000 Current Time – Recorded Time = Age of Data 8:00 am December 12, 2000 – 2:00 am December 12, 2000 = 0 days, 6 hours, 0 minutes Age of Data: 0 days, 6 hours, 0 minutes . Copyright © 2001 Stevens Institute of Technology, CIESE, All Rights Reserved. Version 2.1 ANSWER KEY Example 2: Time/Date Stamp: 14 JAN 01 18:45 GMT Current Time: January 15, 2001 4:30 pm Location: Hoboken, NJ 14 JAN 01 = January 14, 2001 GMT – 5 hours = EST 18:45 GMT – 5 hours = 13:45 EST 13:45 GMT = 1:45 pm EST, therefore . Time and Date the data was recorded: 1:45 pm January 14, 2001 . Current Time – Recorded Time = Age of Data 4:30 pm January 15, 2001 – 1:45 pm January 14, 2001 = 0 days, 26 hours, 45 minutes Age of Data: 1 day, 2 hours, 45 minutes . Converting Time/Date Stamps Practice Using what you’ve already learned, determine when that data was taken and the “age” of the data. If you have any problems while completing this activity, e-mail or ask your Workshop Leader in the next workshop. 1. Time/Date Stamp: 05 JAN 01 15:20 UTC Current Time: January 5, 2001 3:00 pm Location: Miami, FL 05 JAN 01 = January 05, 2001 UTC – 5 hours = EST 15:20 UTC – 5 hours = 10:20 UTC 10:20 UTC = 10:20 am EST, therefore . Time and Date the data was recorded: ___10:20 am, January 05, 2001 . Current Time – Recorded Time = Age of Data 3:00 pm January 5, 2001 - 10:20 am January 05, 2001= 0 days, 4 hours, 40 minutes Age of Data: ________0 days, 4 hours, 40 minutes . Copyright © 2001 Stevens Institute of Technology, CIESE, All Rights Reserved. Version 2.1 ANSWER KEY 2. Time/Date Stamp: 31 DEC 00 05:20 GMT Current Time: January 1, 2001 9:00 am Location: Phoenix, AZ (Phoenix does NOT use Daylight Saving Time) 31 DEC 00 = December 31, 2000 GMT – 7 hours = MST (Arizona does NOT observe Daylight Saving Time) 5:20 GMT – 7 hours = 22:20 GMT of the day before, i.e. December 30th 22:20 GMT = 10:20 pm MST, therefore . Time and Date the data was recorded: ___10:20 pm, December 30, 2000 . Current Time – Recorded Time = Age of Data Date Total Time 1/01 9 hours 12/31 24 hours 9:00 am January 01, 2001 - 10:20 pm, Dec. 30, 2000 = 12/30 1 hour, 40 min. 1 day, 12 hours, 40 minutes Total 34 hours, 40 min. Age of Data: ________1 day, 10 hours, 40 minutes . 3. Time/Data Stamp: 22 JUL 00 22:30 Z Current Time: July 25, 2000 11:30 pm Location: Cleveland, OH 22 JUL 00 = July 22, 2000 Z – 4 hours = EDT 22:30 Z – 4 hours = 18:30 Z 18:30 Z = 6:30 pm EDT, therefore . Time and Date the data was recorded: ___6:30 pm, July 22, 2000 . Date Total Time Current Time – Recorded Time = Age of Data 6/25 23 hours, 30 min. 6/24 24 hours 11:30 pm July 25, 2000 - 6:30 pm, July 22, 2000 = 6/23 24 hours 6/22 5 hours, 30 min. 3 days, 5 hours, 0 minutes Total 77 hours Age of Data: ________3 days, 5 hours, 0 minutes _ Copyright © 2001 Stevens Institute of Technology, CIESE, All Rights Reserved. Version 2.1 .