Work out the time anywhere with a time-zone map

Grade 9 Social Studies Worksheet

Circle the best answer.

1. Read this first

   Use this

   Card A. Offsets in July, and when clocks change. Charleston: UTC−4 in summer (Eastern Daylight Time, from the second Sunday in March to the first Sunday in November), UTC−5 in winter. London: UTC+1 in summer (British Summer Time, from the last Sunday in March to the last Sunday in October), UTC+0 in winter. Phoenix: UTC−7 all year (Arizona, apart from the Navajo Nation, has not changed clocks since 1968); the Navajo Nation, in northeast Arizona, does change its clocks. Tokyo UTC+9 and Beijing UTC+8: no daylight saving time. Moscow UTC+3 all year since 2014. Sydney: UTC+10 in winter, UTC+11 in summer, from the first Sunday in October to the first Sunday in April. Card B. The 2027 calendar for those Sundays. Second Sunday in March: 14 March. Last Sunday in March: 28 March. First Sunday in April: 4 April. First Sunday in October: 3 October. Last Sunday in October: 31 October. First Sunday in November: 7 November. Clocks change on the Sunday itself.

2. 1.

   By how many hours is London ahead of Charleston on 20 March 2027, Ari asks?

   • 4 hours: Charleston has changed its clocks and London has not yet
   • 5 hours, the gap in January and in July, as for most of the year
   • 6 hours: London has changed and Charleston has not, so London is further ahead
   • 1 hour, the size of the single clock change made by this date

3. Use this

   Card A. Offsets in July, and when clocks change. Charleston: UTC−4 in summer (Eastern Daylight Time, from the second Sunday in March to the first Sunday in November), UTC−5 in winter. London: UTC+1 in summer (British Summer Time, from the last Sunday in March to the last Sunday in October), UTC+0 in winter. Phoenix: UTC−7 all year (Arizona, apart from the Navajo Nation, has not changed clocks since 1968); the Navajo Nation, in northeast Arizona, does change its clocks. Tokyo UTC+9 and Beijing UTC+8: no daylight saving time. Moscow UTC+3 all year since 2014. Sydney: UTC+10 in winter, UTC+11 in summer, from the first Sunday in October to the first Sunday in April. Card B. The 2027 calendar for those Sundays. Second Sunday in March: 14 March. Last Sunday in March: 28 March. First Sunday in April: 4 April. First Sunday in October: 3 October. Last Sunday in October: 31 October. First Sunday in November: 7 November. Clocks change on the Sunday itself. Card C. Harlow Books (made up) has offices in Charleston and London. Staff in both work from 9:00 to 17:00 on their own local clocks.

4. 2.

   How many hours a day do the two offices’ working hours overlap on 20 March 2027, Bo asks?

   • 8 hours, since both offices work the same 9:00 to 17:00 day
   • 4 hours: London 13:00 to 17:00 is Charleston 9:00 to 13:00
   • 3 hours, the overlap for most of the year when the gap is 5 hours
   • 5 hours, the usual gap between the two offices’ clocks
5. 3.

   In 2027, on how many calendar days is the London–Charleston gap 4 hours, counting both short periods, Esme asks?

   • 28 days: two weeks in March and two in autumn, since each change is two weeks apart
   • 21 days: 14 to 27 March, and 31 October to 6 November
   • 7 days, the autumn week when the two places have changed on different Sundays
   • 14 days, since the gap is 4 hours in the spring weeks and at no other time

6. Use this

   Card D. Dara (made up for practice) uses one offset, UTC+3, for the whole country. The east city Kell and the west city Orm lie at the same latitude, 45° of longitude apart. Earth turns 15° an hour, so 1° of longitude is 4 minutes of sun time. In midsummer the sun rises in Kell at 04:30 on the clock. A government report says one zone makes trade easier because the offices in both cities keep the same clock time.

7. 4.

   Who bears the cost of Dara’s single zone, Jun asks?

   • Eastern residents, since Kell’s sun comes later on the clock than Orm’s
   • Western residents: Orm’s sun comes about three hours later on the clock
   • No one, since one zone puts the clocks on one sun time as well
   • Traders, since one zone adds a three-hour clock gap between the two cities
8. 5.

   Dara’s report says one zone helps trade. What does the zone give and what does it cost, Luz asks?

   • Trade gets one clock; the cost is sun time that differs by about three hours
   • Trade gets one clock and the sun matches in both cities, so it costs nothing
   • Trade loses from a three-hour clock gap, while sun time matches
   • Trade gets one clock, and the sun rises in Orm at 04:30 as in Kell

9. Use this

   Card B. The 2027 calendar for those Sundays. Second Sunday in March: 14 March. Last Sunday in March: 28 March. First Sunday in April: 4 April. First Sunday in October: 3 October. Last Sunday in October: 31 October. First Sunday in November: 7 November. Clocks change on the Sunday itself. Card E. A made-up firm has offices in Phoenix, Charleston and London. Staff work 9:00 to 17:00 local time. Phoenix is UTC−7 all year. Charleston is UTC−5 in winter and UTC−4 from 14 March 2027. London is UTC+0 in winter and UTC+1 from 28 March 2027.

10. 6.

    On 20 March 2027, how many hours a day are all three offices at work at once, Milo asks?

    • 4 hours, the overlap that London and Charleston have on their own
    • 1 hour: 16:00 in London, 12:00 in Charleston, 9:00 in Phoenix
    • 3 hours, the clock gap between Phoenix and Charleston on that date
    • No hour, since three offices on three offsets cannot share a working hour
11. 7.

    Noah’s note says: “On 30 March 2027 the three offices still share an hour, as on 20 March.” Which fix is right?

    • Change it: Phoenix moved its clocks forward, so the shared hour is gone
    • Leave it: Phoenix did not change, so the shared hour stays the same
    • Change it: Charleston changed on 14 March, so the shared hour is gone
    • Change it: London moved on 28 March, so its day ends when Phoenix’s starts

12. Use this

    Card A. Offsets in July, and when clocks change. Charleston: UTC−4 in summer (Eastern Daylight Time, from the second Sunday in March to the first Sunday in November), UTC−5 in winter. London: UTC+1 in summer (British Summer Time, from the last Sunday in March to the last Sunday in October), UTC+0 in winter. Phoenix: UTC−7 all year (Arizona, apart from the Navajo Nation, has not changed clocks since 1968); the Navajo Nation, in northeast Arizona, does change its clocks. Tokyo UTC+9 and Beijing UTC+8: no daylight saving time. Moscow UTC+3 all year since 2014. Sydney: UTC+10 in winter, UTC+11 in summer, from the first Sunday in October to the first Sunday in April.

13. 8.

    A call is set for 9:00 in Phoenix in July. Which cities have it between 8:00 and 18:00 on their clocks, Pia asks?

    • Tokyo (01:00) and Beijing (00:00), the next cities east
    • Charleston alone (12:00), since London is too far east
    • Charleston, London and Beijing (00:00)
    • Charleston (12:00) and London (17:00)

14. Use this

    Card F. The International Date Line runs roughly along 180°, but it bends. In 1995 Kiribati, whose islands lie on both sides of 180°, had the line moved east so that all its islands share one date.

15. 9.

    Tala’s note says: “The date line bends because Earth’s surface is curved.” Which fix is right?

    • Change it: it bends so each time zone is exactly 15° wide on the map
    • Change it: it bends to follow the lines of latitude across the ocean
    • Leave it: a flat map must bend any line that is drawn on a sphere, so the bend has no other reason
    • Change it: it bends so places that work together share a date

16. Use this

    Card D. Dara (made up for practice) uses one offset, UTC+3, for the whole country. The east city Kell and the west city Orm lie at the same latitude, 45° of longitude apart. Earth turns 15° an hour, so 1° of longitude is 4 minutes of sun time. In midsummer the sun rises in Kell at 04:30 on the clock. A government report says one zone makes trade easier because the offices in both cities keep the same clock time. Card G. A survey of Dara (made up). Share of workers whose winter workday starts before sunrise: 70 percent in the west, 20 percent in the east. Firms in both cities say one clock makes orders easier to handle.

17. 10.

    Zee’s note says: “One zone helps everyone in Dara equally.” Which fix is right?

    • Change it: firms gain a clock, but dark starts are 70 percent west, 20 east
    • Change it: more eastern workers start in the dark, 70 percent against 20 in the west
    • Leave it: 70 and 20 percent average 45 percent, a fair share for each side
    • Leave it: firms in both cities say one clock makes orders easier to handle