Ferdinand de Saussure, Swiss linguist: the signifier and signified
The Living Philosophy (2021). What is Semiotics? Saussure on Langue/Parole and Signifier/Signified. Youtube video (15min). Discusses the distinction between synchronic and diachronic linguistics, langue and parole, signifier and signified.
Roman Jakobson, Russian-American linguist: six functions of language
Peterson, M (2018). ATH175 Language functions. Youtube video (3min). Simple explanation of the six factors (elements) of language and how they correspond to the six functions of language.
Critical learning period in language acquisition
Secrets of the wild child (1995). ClickView video (55min). 1970 in the Los Angeles suburb of Arcadia, social workers in took custody of a 13 year old child who had spent much of her life chained to a potty chair in her bedroom. She could not speak, walk, or respond to other people. She was called "Genie." Her case attracted psychologists who were interested in finding out whether she could still learn to speak.
Michael Tomasello's usage based theory of language acquisition