Human beings are prewired for language. As infants we begin to learn language as the direct result of hearing it, not as a result of formal instruction. The process, called natural language acquisition, moves through a series of distinct developmental stages ending in basically adult-level language use in pronunciation and vocabulary in as soon as five years. The learner's language is profoundly influenced by language environment, including factors such as geographical region, ethnicity, and social grouping, all of whose characteristics shape the speaker's language use in distinct ways.
Mastery of Standard English, on the other hand, requires formal instruction. The focus is on getting everyone to use a single variety of English in public settings for sake of clear communication. Students must learn rules for how to pronounce and spell words and use them in sentences. They must learn how to speak and write English following specific forms and levels of formality, depending on the occasion and audience. They must learn how to read a variety of Standard English texts for a variety of purposes. Mastery of Standard English is an important mark of education and is expected of employees in the workplace and in a variety of other public settings.
