Proto-Indo-European language

Proto-Indo-European (PIE) is the linguistic reconstruction of the common ancestor of the Indo-European languages. PIE was the first proposed proto-language to be widely accepted by linguists. Far more work has gone into reconstructing it than any other proto-language, and it is by far the best understood of all proto-languages of its age. During the 19th century, the vast majority of linguistic work was devoted to reconstruction of Proto-Indo-European or its daughter proto-languages such as Proto-Germanic, and most of the current techniques of linguistic reconstruction in historical linguistics (e.g. the comparative method and the method of internal reconstruction) were developed as a result. These methods supply all of our knowledge concerning PIE, since there is no written record of the language.

Scholars estimate that PIE may have been spoken as a single language (before divergence began) around 3500 BC, though estimates by different authorities can vary by more than a millennium. A number of hypotheses have been proposed for the origin and spread of the language, the most popular among linguists being the Kurgan hypothesis, which postulates an origin in the Pontic–Caspian steppe of Eastern Europe. Features of the culture of the speakers of PIE, known as Proto-Indo-Europeans, have also been reconstructed based on the shared vocabulary of the early attested Indo-European languages.

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.

Indo-European languages

The Indo-European languages are a family of several hundred related languages and dialects. There are about 445 living Indo-European languages, according to the estimate by Ethnologue, with over two-thirds (313) of them belonging to the Indo-Iranian branch. The Indo-European family includes most major current languages of Europe, and parts of Western, Central and South Asia. It was also predominant in ancient Anatolia (present-day Turkey), and the ancient Tarim Basin (present-day Northwest China) and most of Central Asia until the invasion and migrations of Turkic speakers especially during the Mongol–Turkic conquest in the 13th century. With written evidence appearing since the Bronze Age in the form of the Anatolian languages and Mycenaean Greek, the Indo-European family is significant to the field of historical linguistics as possessing the second-longest recorded history, after the Afroasiatic family.

Several disputed proposals link Indo-European to other major language families.