This document discusses the application of linguistics to language teaching. It covers pedagogical grammar and its use in teaching native and second languages. It describes the rise and fall of the audiolingual method for teaching second languages and introduces Krashen's theory of acquisition vs learning. Krashen proposed the natural approach to create an anxiety-free environment where students can acquire a second language through comprehensible input, communication, and activities rather than focusing on grammar rules. The document also discusses dialect, sentence combining techniques, and the role of theory in second language teaching.