## Time and Again

Mathematics, Measurement (includes Time)

Grade 5- 8

### Objective

Students will learn about historical time and make time lines.

### Directions

Historical Time
There are two main divisions of time--time roughly reckoned before and after the birth of Christ. Most of the time in the ancient world is recorded as b.c. (before Christ). Some books use b.c.e. (before the common era). This time record counts backwards from the approximate date of Christ's birth until the earliest dates in recorded history. The bigger the number named with b.c. or b.c.e., the further back in time the event occurred. Numerical dates in b.c. become smaller as they approach the present so 44 b.c. is much closer to the present than 3500 b.c. (The small c. is read "circa" and indicates an approximate date.)
Examples

 c. 2000 b.c.--Invention of the shadow clock c. 100 b.c.--Birth of Julius Caesar 44 b.c.--Death of Julius Caesar

The invention of the shadow clock about 2000 b.c. happened 1,900 years before the birth of Julius Caesar in 100 b.c.
a.d. or c.e.
a.d. (anno Domini) dates events from the approximate time of the birth of Christ. Anno Domini is a Latin expression meaning "in the year of Our Lord." The year 2000 a.d. is about 2,000 years since the birth of Christ. The abbreviation c.e. (common era) means exactly the same time as a.d. The year 2000 can be written as 2000 a.d. or 2000 c.e. Some books use c.e. and others use a.d. Numerical dates in a.d. (or c.e.) become larger so 1999 a.d. is much closer to the present than
730 a.d.
Time Lines
Times lines are a way of illustrating the length of historical time.
• Dates followed by b.c. descend from larger to smaller.
• There is no year 0.
• Dates followed by a.d. rise from smaller to larger.

Look at the time line below.
 c. 8000 b.c. Agriculture is invented in Mesopotamia. c. 5000 b.c. Crop irrigation is invented in Mesopotamia. c. 3100 b.c. The Egyptians invent an early form of writing. c. 1800 b.c. The Babylonians develop multiplication tables. c. 700 b.c. The Chinese begin keeping records of comets. 214 b.c. Construction begins on the Great Wall of China. 27 b.c. Construction begins on the Roman Pantheon. b.c. a.d. 79 a.d. Mount Vesuvius erupts and buries Pompeii. 868 a.d. The first printed book is made in China. c. 1348 a.d. Bubonic plague sweeps through Europe and Asia. 1775 a.d. The American Revolution begins. 1969 a.d. The first manned moon landing occurs.

### Resources

• Time and Again activity sheets
• pencils

• ## Monthly Spotlight

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