CONCEPTS
Language Acquisition Concepts
Clear, interactive explanations of the core concepts behind learning a language through comprehensible input — each with a self-check quiz.
Comprehensible Input
Comprehensible input is language a learner can understand despite not knowing every word — typically described as input one step beyond the learner's current level (i + 1) — and it is the central condition for acquiring a second language according to Stephen Krashen's input hypothesis.
Krashen HypothesesThe Input Hypothesis
The input hypothesis is Stephen Krashen's theory that a second language is acquired in only one way — by understanding messages slightly above the learner's current level (i + 1) — and that comprehension, not output or grammar study, is what causes acquisition.
ResearchersStephen Krashen
Stephen Krashen is an American linguist and educational researcher, professor emeritus at the University of Southern California, best known for his theory of second-language acquisition and the concept of comprehensible input.
Krashen HypothesesThe Affective Filter Hypothesis
The affective filter hypothesis is Krashen's claim that emotions such as anxiety, low motivation, and low self-confidence act as a mental "filter" that can block comprehensible input from being acquired, even when the input itself is understood.
Methods & ApproachesThe Natural Approach
The Natural Approach is a language teaching method developed by Stephen Krashen and Tracy Terrell that applies the input hypothesis in the classroom: it emphasises large amounts of comprehensible input, a low-anxiety environment, and a silent period before speaking, rather than grammar drills and forced production.
Methods & ApproachesExtensive Reading
Extensive reading is an approach to language learning in which learners read large amounts of easy, enjoyable material — typically at or just below their level — for the purpose of overall comprehension and pleasure rather than detailed word-by-word study.
Methods & ApproachesFree Voluntary Reading
Free voluntary reading (FVR) is reading whatever you want, whenever you want, stopping when you lose interest — proposed by Stephen Krashen as one of the most powerful and enjoyable sources of comprehensible input for both literacy and language acquisition.
Methods & ApproachesThe Output Hypothesis
The output hypothesis, proposed by Merrill Swain, states that producing language (speaking or writing) also drives acquisition — not only comprehension of input — because it forces learners to notice gaps in their knowledge, test hypotheses about the language, and reflect on how the language works.
Methods & ApproachesSpaced Repetition
Spaced repetition is a learning technique in which items are reviewed at increasing time intervals — with items you know well reviewed less often and items you struggle with reviewed more often — based on the principle that memory is strengthened most efficiently just before it would otherwise be forgotten.
Methods & ApproachesTPRS (Teaching Proficiency through Reading and Storytelling)
TPRS (Teaching Proficiency through Reading and Storytelling) is a comprehensible-input teaching method developed by Blaine Ray in which the teacher co-creates and repeats compelling, personalised stories with students to deliver high volumes of i + 1 input in an engaging, low-anxiety classroom.
Methods & ApproachesLanguage Transfer
Language Transfer is a free audio language course series created by Mihalis Eleftheriou that teaches languages through a Socratic thinking method — prompting learners to work out the target language themselves from their existing knowledge — rather than through memorisation or grammar tables.
Frameworks & ToolsCEFR — Common European Framework of Reference for Languages
The Common European Framework of Reference for Languages (CEFR) is an international standard published by the Council of Europe that describes language proficiency on six levels — A1, A2, B1, B2, C1, C2 — from complete beginner to near-native mastery, used worldwide for teaching, testing, and certification.
Frameworks & ToolsCEFR A1 — Beginner English
CEFR A1 is the entry level of the Common European Framework — a Beginner who can understand and use very basic phrases to introduce themselves and describe familiar things, provided the other person speaks slowly and clearly.
Frameworks & ToolsCEFR B1 — Intermediate English
CEFR B1 is the Intermediate level — the "threshold" — at which a learner can understand the main points of clear standard input on familiar topics, deal with most situations likely to arise while travelling, and produce simple connected text on familiar subjects.
Frameworks & ToolsCEFR C1 — Advanced English
CEFR C1 is the Advanced level at which a learner can understand a wide range of demanding, longer texts and recognise implicit meaning, express ideas fluently and spontaneously without much searching for expressions, and use language flexibly and effectively for social, academic, and professional purposes.
Krashen HypothesesSilent Period
The silent period is the early phase of second-language acquisition during which a learner absorbs language through listening and comprehension before producing any spoken output — a concept associated with Stephen Krashen, who argued that premature pressure to speak interferes with natural acquisition.
Krashen HypothesesMonitor Hypothesis
The monitor hypothesis is one of Stephen Krashen's five hypotheses of second-language acquisition, proposing that consciously learned grammar rules function as an "editor" or monitor that can check and correct output produced by the acquired system — but only when the learner has sufficient time, focuses on form, and knows the rule.
Methods & ApproachesTotal Physical Response
Total Physical Response (TPR) is a language teaching method developed by psychologist James Asher in the 1960s in which learners acquire language by listening to commands in the target language and responding with physical actions — connecting language to movement and reducing the anxiety of early production.
Methods & ApproachesCommunicative Language Teaching
Communicative Language Teaching (CLT) is an approach to second-language education that emphasises real communicative interaction as both the means and goal of learning — prioritising meaningful use of language over rote repetition of grammar forms, and treating fluency as more important than formal accuracy in the early stages.
Krashen HypothesesAcquisition–Learning Distinction
Krashen's acquisition–learning distinction (1982) holds that adults have two independent systems for developing language competence: subconscious acquisition (identical to how children learn L1) and conscious learning (explicit knowledge of rules). Only acquired knowledge drives fluent, spontaneous speech.
Krashen Hypothesesi+1 (Comprehensible Input)
i+1 is Krashen's formula for optimal comprehensible input: language slightly beyond the learner's current level (i), where "i" represents current competence and "+1" is the next learnable element understood through context.
Methods & ApproachesNoticing Hypothesis
The noticing hypothesis (Schmidt, 1990) states that conscious attention to input features is necessary for second language acquisition — unnoticed input does not convert to intake.
Methods & ApproachesInteraction Hypothesis
The interaction hypothesis (Long, 1981; updated 1996) proposes that meaning negotiation during conversational interaction facilitates SLA by making input comprehensible and directing learner attention to gaps between interlanguage and target forms.
ResearchersMerrill Swain
Merrill Swain (born 1942) is a Canadian applied linguist best known for the Output Hypothesis — the theory that producing language, not only comprehending it, is necessary for full second language acquisition.
ResearchersPaul Nation
Paul Nation (born 1942) is a New Zealand applied linguist whose research on vocabulary acquisition established the foundational principles of vocabulary learning through extensive reading, word frequency, and spaced repetition.