--- title: The date line and summer time: clocks going forward and back — a lesson of Mova's school · trees and pragmatics description: «The date line and summer time: clocks going forward and back», a lesson of the world course of Mova's primary school, sentence by sentence with dependency trees and pragmatics. It begins: Somewhere the date has to change, or a traveller going east round the world would keep adding hours forever. --- [Mova](https://md.mova.elamur.ai/free/en/) · [this page in HTML](https://mova.elamur.ai/free/en/corpora/school/world/121-date-line-and-summer-time/) [home](https://md.mova.elamur.ai/free/en/) / [corpora](https://md.mova.elamur.ai/free/en/corpora/) / [school](https://md.mova.elamur.ai/free/en/corpora/school/) / [World](https://md.mova.elamur.ai/free/en/corpora/school/world/) / The date line and summer time: clocks… # The date line and summer time: clocks going forward and back Lesson 121 of the world course of Mova's primary school: 18 sentences, each with its syntax tree and pragmatics. The lessons are written for Mova, and their agreed trees are part of Mova corpus 0.4 (CC BY-SA 4.0). How Mova does on its tests: [the lesson at school](https://md.mova.elamur.ai/free/en/school-run/world/121-date-line-and-summer-time/). - [0](https://md.mova.elamur.ai/free/en/corpora/school/world/121-date-line-and-summer-time/0/) — Somewhere the date has to change, or a traveller going east round the world would keep adding hours forever. - [2](https://md.mova.elamur.ai/free/en/corpora/school/world/121-date-line-and-summer-time/2/) — Places just west of it, like Kiribati, Samoa and New Zealand, see each new day first; cross it going east and the date goes back one day, going west and it jumps forward one. - [4](https://md.mova.elamur.ai/free/en/corpora/school/world/121-date-line-and-summer-time/4/) — Kiritimati, an island in Kiribati, is 14 hours ahead of London, so when it hits midnight there, it's still 10 am on 31 December in London. - [5](https://md.mova.elamur.ai/free/en/corpora/school/world/121-date-line-and-summer-time/5/) — Summer time, called British Summer Time in the UK and Daylight Saving Time in the USA, moves the clocks forward 1 hour in spring so evenings stay light longer, and back again in autumn. - [6](https://md.mova.elamur.ai/free/en/corpora/school/world/121-date-line-and-summer-time/6/) — "Spring forward, fall back" ("fall" is American for autumn): the spring night is only 23 hours long, the autumn night 25. - [7](https://md.mova.elamur.ai/free/en/corpora/school/world/121-date-line-and-summer-time/7/) — A builder, William Willett, pushed for it in Britain from 1907, because he hated seeing curtains closed on bright summer mornings; Germany and then Britain started it in 1916, during the First World War, to save coal. - [8](https://md.mova.elamur.ai/free/en/corpora/school/world/121-date-line-and-summer-time/8/) — Not everyone does it: most of Arizona doesn't, and people still argue whether it's worth it. - [9](https://md.mova.elamur.ai/free/en/corpora/school/world/121-date-line-and-summer-time/9/) — Phones change by themselves; ovens, cars and kitchen clocks need doing by hand, or they're an hour out for half the year. - [10](https://md.mova.elamur.ai/free/en/corpora/school/world/121-date-line-and-summer-time/10/) — The International Date Line runs mostly through the Pacific Ocean; it is where one date changes to the next. - [11](https://md.mova.elamur.ai/free/en/corpora/school/world/121-date-line-and-summer-time/11/) — Crossing the date line going east, the date goes back 1 day; going west, it goes forward 1 day. - [12](https://md.mova.elamur.ai/free/en/corpora/school/world/121-date-line-and-summer-time/12/) — Kiritimati in Kiribati is 14 hours ahead of London in winter, so its New Year midnight comes at 10 am on 31 December in London. - [15](https://md.mova.elamur.ai/free/en/corpora/school/world/121-date-line-and-summer-time/15/) — In Britain the clocks go forward 1 hour at 1 am on the last Sunday of March and back 1 hour at 2 am on the last Sunday of October. - [16](https://md.mova.elamur.ai/free/en/corpora/school/world/121-date-line-and-summer-time/16/) — "Spring forward, fall back" helps you remember which way the clocks go; "fall" is the American word for autumn. - [17](https://md.mova.elamur.ai/free/en/corpora/school/world/121-date-line-and-summer-time/17/) — The night the clocks go back has 25 hours, and the night they go forward has 23. - [18](https://md.mova.elamur.ai/free/en/corpora/school/world/121-date-line-and-summer-time/18/) — Summer time is called British Summer Time in the UK and Daylight Saving Time in the USA. - [19](https://md.mova.elamur.ai/free/en/corpora/school/world/121-date-line-and-summer-time/19/) — The USA moves its clocks forward on the second Sunday of March, so for 2 or 3 weeks New York is 4 hours behind London, not 5. - [20](https://md.mova.elamur.ai/free/en/corpora/school/world/121-date-line-and-summer-time/20/) — Most of Arizona does not use summer time, so in summer it has the same time as California and in winter it is 1 hour ahead. - [21](https://md.mova.elamur.ai/free/en/corpora/school/world/121-date-line-and-summer-time/21/) — William Willett, a British builder, pushed for summer time from 1907; Britain started it in 1916, 9 years later, a few weeks after Germany. - ← previous: [Time zones: why it's night in Sydney when it's day in London](https://md.mova.elamur.ai/free/en/corpora/school/world/120-time-zones/) - next →: [Clocks before clocks: sundials, water clocks, candles and hourglasses](https://md.mova.elamur.ai/free/en/corpora/school/world/122-clocks-before-clocks/) - ↑ back to [World](https://md.mova.elamur.ai/free/en/corpora/school/world/)