Using Timelines to Understand

History

The Gregorian Calendar

• Invented by the Romans.• Improved by Pope Gregory XIII –

he added Leap Year.• Events are relative the date that

Christians believed Jesus was born.

Other CalendarsIt is currently the year:• 2014 on the Christian calendar• 5775 on the Hebrew calendar• 1435 AH on the Islamic calendar• Year of the Horse on the Chinese

calendar

The Gregorian Calendar

• BC = “Before Christ”• AD = “Anno Domini”– No, it does not mean “after death”.– Latin meaning: “the year of our lord”.– This year is 2014 years since

Christians believe Jesus was born.

The New System• BCE means “Before the Common

Era”44 BCE = 44 BC

• CE means “Common Era”2014 CE = 2014 AD

Similar to Number Lines

0-2 -1 1 2

1 CE2 BCE 1 BCE 2 CE 3 CE

Relative Time• YA = “years ago”• Dinosaurs died out 65 million YA• Earliest humans: 4 million YA

Rough Estimates of Dates

• Ca. = circa = “around the time of”• Remember: circa sounds like

“circle” which is round.• First stone tools were made ca. 2

million years ago.

http://nationalgeographic.com