Khan Academy
Khan Academy: Greco Roman
Instead of rule by a single person, Athens and Rome developed governments with widespread participation by male elites, which lasted about 170 years in Athens and about 480 years in Rome. This article discusses the rise of the Greek and...
Khan Academy
Khan Academy: Common Questions About Dates
Our calendar is called the Gregorian calendar and was instituted by Pope Gregory XIII in 1582. There are many other calendars. Learn about these calendars and the meanings of B.C.E and C.E.
Math Is Fun
Math Is Fun: Ad and Bc
The resource examines how years are written. Topics discussed include "Common Era" and "Before Common Era".