Time scale

Time scale may refer to:

In astronomy and physics:

In cosmology and particle physics:

Khan Academy

Khan Academy is a non-profit educational organization created in 2006 by educator Salman Khan with the aim of providing a free, world-class education for anyone, anywhere. The organization produces short lectures in the form of YouTube videos. In addition to micro lectures, the organization's website features practice exercises and tools for educators. All resources are available for free to anyone around the world. The main language of the website is English, but the content is also available in other languages.

History

The founder of the organization, Salman Khan, was born in New Orleans, Louisiana, United States to immigrant parents from Bangladesh and India. After earning three degrees from the Massachusetts Institute of Technology (a BS in mathematics, a BS in electrical engineering and computer science, and an MEng in electrical engineering and computer science), he pursued an MBA from Harvard Business School.

In late 2004, Khan began tutoring his cousin Nadia who needed help with math using Yahoo!'s Doodle notepad.When other relatives and friends sought similar help, he decided that it would be more practical to distribute the tutorials on YouTube. The videos' popularity and the testimonials of appreciative students prompted Khan to quit his job in finance as a hedge fund analyst at Connective Capital Management in 2009, and focus on the tutorials (then released under the moniker "Khan Academy") full-time.

Geologic time scale

The geological time scale (GTS) is a system of chronological measurement that relates stratigraphy to time, and is used by geologists, paleontologists, and other Earth scientists to describe the timing and relationships between events that have occurred throughout Earth’s history. The table of geologic time spans presented here agrees with the nomenclature, dates and standard color codes set forth by the International Commission on Stratigraphy.

Evidence from radiometric dating indicates that Earth is about 4.54 billion years old. The geology or deep time of Earth’s past has been organized into various units according to events which took place in each period. Different spans of time on the GTS are usually delimited by changes in the composition of strata which correspond to them, indicating major geological or paleontological events, such as mass extinctions. For example, the boundary between the Cretaceous period and the Paleogene period is defined by the Cretaceous–Paleogene extinction event, which marked the demise of the non-avian dinosaurs and many other groups of life. Older time spans which predate the reliable fossil record (before the Proterozoic Eon) are defined by the absolute age.

Scale

Scale or scales may refer to:

Common meanings

Places

Mathematics

Science

Academy

An academy (Attic Greek: Ἀκαδήμεια; Koine Greek Ἀκαδημία) is an institution of secondary education or higher learning, research, or honorary membership. The name traces back to Plato's school of philosophy, founded approximately 385 BC at Akademia, a sanctuary of Athena, the goddess of wisdom and skill, north of Athens, Greece.

The original Academy

Before Akademia was a school, and even before Cimon enclosed its precincts with a wall, it contained a sacred grove of olive trees dedicated to Athena, the goddess of wisdom, outside the city walls of ancient Athens. The archaic name for the site was Hekademia, which by classical times evolved into Akademia and was explained, at least as early as the beginning of the 6th century BC, by linking it to an Athenian hero, a legendary "Akademos". The site of Akademia was sacred to Athena and other immortals.

Plato's immediate successors as "scholarch" of Akademia were Speusippus (347–339 BC), Xenocrates (339–314 BC), Polemon (314–269 BC), Crates (ca. 269–266 BC), and Arcesilaus (ca. 266–240 BC). Later scholarchs include Lacydes of Cyrene, Carneades, Clitomachus, and Philo of Larissa ("the last undisputed head of the Academy"). Other notable members of Akademia include Aristotle, Heraclides Ponticus, Eudoxus of Cnidus, Philip of Opus, Crantor, and Antiochus of Ascalon.