Stephen Krashen’s Theory of Second Language Acquisition

Introduction

Stephen D. Krashen (born May 14, 1941) is an American linguist and educational researcher whose work has significantly influenced discussions of second language acquisition (SLA) and language teaching. A professor emeritus at the University of Southern California, Krashen developed his influential Monitor Model during the 1970s and 1980s to explain how people acquire additional languages and what factors may influence this process.

Krashen’s model consists of five hypotheses: the Acquisition-Learning Hypothesis, the Natural Order Hypothesis, the Monitor Hypothesis, the Input Hypothesis and the Affective Filter Hypothesis.

These hypotheses have had a lasting influence on language teaching, particularly discussions of meaningful communication, comprehensible input and the emotional conditions that may support language acquisition. However, some of Krashen’s claims remain debated among researchers. Understanding his ideas alongside other perspectives on language learning can help teachers evaluate their practical applications critically.

Krashen’s work has contributed to discussions about how learners develop communicative competence, the relationship between conscious grammar study and language acquisition, and the importance of exposure to language that learners can understand.

These ideas have practical relevance for English-language teacher training. At EBC, trainees develop the skills required to teach English through English, rather than relying on their learners’ native language. An important part of this preparation is the Trinity CertTESOL course unit known as Unknown Foreign Language, which gives trainees first-hand experience of learning a language they do not speak.

This article explains Krashen’s five hypotheses, explores their implications for English-language teaching and considers how EBC’s training approach, including the Unknown Foreign Language unit, helps trainees reflect on the experience of learning a new language.

The five hypotheses of Krashen’s Theory of Second Language Acquisition

Krashen’s Monitor Model is based on five main hypotheses:

1. The Acquisition-Learning Hypothesis: distinguishes between acquiring a language through meaningful communication and consciously learning its rules.
2. The Natural Order Hypothesis: proposes that certain grammatical features tend to be acquired in a relatively predictable order.
3. The Monitor Hypothesis: explains how consciously learned rules may be used to check or edit language production.
4. The Input Hypothesis: emphasises exposure to language that learners can understand and that contains elements slightly beyond their current level.
5. The Affective Filter Hypothesis: proposes that emotional factors may influence how receptive learners are to language input.

Together, these hypotheses offer a framework for thinking about language acquisition. They should not, however, be treated as a complete or universally accepted explanation of every aspect of language learning.

1. The Acquisition-Learning Hypothesis

Krashen proposed that people develop second-language competence through two distinct processes: acquisition and learning.

Acquisition refers to developing language ability through meaningful exposure and communication. Learners encounter and use language to understand messages and express meaning, without necessarily concentrating consciously on grammatical rules. For example, an English learner may gradually become familiar with common sentence patterns by listening to conversations, reading stories and participating in classroom activities.

Learning, by contrast, refers to consciously studying the language. This may involve analysing grammar rules, memorising vocabulary, completing exercises or learning how a particular sentence structure is formed.

According to Krashen, these processes serve different functions. He argued that acquired language knowledge supports spontaneous communication, while consciously learned knowledge can act as a monitor that helps learners check or edit their language under certain conditions. This distinction is central to his model, although researchers have debated how clearly acquisition and learning can be separated in practice.

For English-language teachers, the hypothesis highlights the importance of giving learners opportunities to understand and use English for meaningful purposes. Grammar explanations and structured exercises may have a place in lessons, but they need not replace activities that involve listening, reading, speaking and writing to communicate.

For example, when teaching the past simple, a teacher might introduce the form and explain how it works, then ask learners to tell a partner about something they did at the weekend. Learners can practise the grammatical structure while focusing on communicating a real message.

Understanding concepts such as interlanguage in language learning can also help teachers recognise that learners develop their own evolving language systems as they work towards greater accuracy and fluency.

2. The Natural Order Hypothesis

The Natural Order Hypothesis proposes that learners tend to acquire certain grammatical features in a relatively predictable order. Krashen argued that this order is not necessarily the same as the order in which grammar rules are taught in a classroom.

Research into second-language acquisition has identified patterns in the development of some grammatical features. However, these patterns do not mean that every learner follows precisely the same sequence or that all grammatical structures can be arranged into one universal order.

The hypothesis suggests that teachers should be cautious about expecting learners to master a grammatical feature simply because it has been explained or practised. Learners may need continued exposure and opportunities to use a structure before they can apply it consistently in spontaneous communication.

For example, a student may understand the rules for forming past-tense sentences during a grammar exercise but continue to make errors when telling a story. This does not necessarily mean that the lesson has failed. It may indicate that the learner needs more opportunities to encounter and use the structure in meaningful contexts.

The Natural Order Hypothesis does not establish a simple universal teaching sequence in which learners must always master one tense before another. Teachers should consider learners’ existing knowledge, communication needs and the demands of the lesson when deciding which language features to introduce and practise.

In practical terms, the hypothesis encourages teachers to recognise developmental progress and avoid interpreting every recurring error as evidence that a learner has not paid attention or has failed to understand an explanation.

3. The Monitor Hypothesis

The Monitor Hypothesis concerns the relationship between consciously learned grammar rules and language production.

Krashen proposed that acquired language knowledge supports spontaneous communication, while consciously learned knowledge can function as a monitor. Learners may use this knowledge to check, correct or edit what they say or write.

In Krashen’s model, three conditions are particularly important for monitor use:

• Sufficient time: learners need time to think about the relevant language rules.
• Attention to accuracy: learners must be concentrating on correctness rather than only on conveying meaning.
• Knowledge of the rule: learners must know the grammatical rule they are trying to apply.

For example, a learner writing a formal email may pause to check whether a verb should be in the past simple or present perfect. The learner is consciously applying grammatical knowledge to review the sentence. In spontaneous conversation, however, there may be less time to consider each rule, so communication may proceed without the same level of conscious checking.

Krashen suggested that excessive reliance on monitoring could interfere with fluency. If learners repeatedly stop to analyse every sentence, their speech may become hesitant and communication more difficult. Nevertheless, self-correction and editing can be valuable in appropriate contexts, particularly in writing and accuracy-focused activities.

Teachers can apply this idea by balancing activities that develop fluency with activities that encourage learners to notice and correct errors. During a fluency task, for instance, a teacher might allow a conversation to continue without interrupting learners for every grammatical mistake. During a later feedback stage, the teacher can address recurring errors and help students refine their language.

The central teaching question is not whether grammar correction should be used, but when and how it can support learners without unnecessarily disrupting communication.

4. The Input Hypothesis

The Input Hypothesis is one of Krashen’s best-known contributions to second-language acquisition theory. It proposes that learners develop language competence when they understand messages containing language features that are slightly beyond their current level.

Krashen expressed this idea using the formula i + 1. In this formula, i represents the learner’s current level of competence, while 1 represents language that extends beyond that level.

The idea is that learners need input they can understand while also encountering some unfamiliar vocabulary, grammatical structures or other language features. If the language is far beyond their ability to understand, they may struggle to follow the message. If it is entirely familiar, it may provide fewer opportunities to encounter new language.

Comprehensible input can come from many sources, including conversations, stories, graded readers, videos, classroom instructions and discussions. Teachers can make input more accessible through context, pictures, gestures, demonstrations, repetition and explanations of key vocabulary.

For example, when teaching a class at elementary level, a teacher might tell a short story using mostly familiar vocabulary and simple sentence structures while introducing a few new expressions. Pictures and actions can help learners follow the story even if they do not understand every word.

The Input Hypothesis also highlights the importance of meaning. Learners need to understand what is being communicated rather than merely encounter unfamiliar language forms without context.

However, the formula i + 1 should not be treated as a precise measurement that teachers can calculate for every learner or lesson. Learners differ in their prior knowledge, interests, language backgrounds and ability to use contextual clues. Teachers therefore need to observe learners’ responses and adjust the level of support and challenge.

In classroom practice, this means providing language that is accessible but not entirely predictable, and creating opportunities for learners to engage with it through meaningful listening, reading and interaction.

5. The Affective Filter Hypothesis

The Affective Filter Hypothesis emphasises the potential influence of emotional factors, including motivation, self-confidence and anxiety, on second-language acquisition.

In Krashen’s model, a high affective filter is associated with conditions that may make learners less receptive to language input, while a low affective filter is associated with conditions more favourable to acquisition. The hypothesis suggests that learners’ emotional experiences may influence how they engage with the language they encounter.

For example, learners who are worried about making mistakes may avoid speaking in front of the class, even when they understand much of the language being used. By contrast, learners who feel supported may be more willing to participate, ask questions and experiment with unfamiliar expressions.

Teachers can help create a supportive learning environment by encouraging participation, responding constructively to mistakes and providing activities that allow learners to build confidence. Pair work and small-group discussions may give some students more opportunities to practise than whole-class speaking alone. Clear instructions and appropriately challenging tasks can also help learners feel more prepared to participate.

The hypothesis does not mean that anxiety or low motivation automatically prevents learning, nor that confidence alone guarantees successful acquisition. Learners respond differently to classroom conditions, and emotional factors interact with other influences on language development.

The practical message for teachers is that the classroom environment matters. Learners need opportunities to participate and use language without feeling that every mistake will be treated as a failure.

This principle also has implications for teacher development. Trainees need to learn how to give clear instructions, respond constructively to learner difficulties and create activities that encourage participation. Experiencing the challenges of being a language learner can help them reflect on these responsibilities.

How comprehensible input connects to EBC’s English-only teaching approach

Krashen’s emphasis on comprehensible input has a clear connection with EBC’s approach to teacher training. Trainees learn to teach English through English rather than relying on translation into their learners’ native language.

This approach requires teachers to develop practical techniques for making meaning clear. Instead of translating a word or grammatical structure, a teacher can use pictures, gestures, real objects, demonstrations, examples, contextual clues and concept-checking questions to help learners understand.

For example, when introducing the word exhausted, a teacher could translate it into the learners’ native language. In an English-only lesson, the teacher might instead show a picture of a tired person, act out being exhausted and provide a contextualised example:

“After running ten kilometres, I was exhausted.”

The teacher could then ask, “Was the runner full of energy, or was the runner very tired?” This checks understanding while keeping the interaction in English.

Similarly, when teaching a grammatical structure, teachers can use timelines, example sentences, contextualised situations and guided questions rather than automatically switching to translation. The objective is not simply to keep the teacher speaking English; it is to make the English being used comprehensible to the learners.

Teaching English through English is a practical skill that needs to be developed and practised. Teachers must learn how to grade their language, anticipate potential comprehension problems, demonstrate activities clearly and check understanding without depending on translation.

EBC’s approach makes this a practical training objective. The theory helps explain why understandable language exposure matters, while teaching practice and feedback help trainees develop the techniques needed to provide it.

The Trinity CertTESOL Unknown Foreign Language unit: learning from the student’s perspective

An especially relevant part of EBC’s Trinity CertTESOL training is the Unknown Foreign Language unit. During this unit, trainees take part in four hours of language lessons in a language that none of them speaks. For example, a teacher might teach the trainees Hindi, using Hindi as the language of instruction throughout the lessons.

The trainees are placed in the position of language learners. They have to follow the teacher’s instructions, work out meanings, respond to questions and participate in activities without being able to rely on their existing knowledge of the language or on explanations in a shared native language.

This experience offers an important opportunity to reflect on what it feels like to learn through a language that is unfamiliar. Trainees may notice which teaching techniques help them understand, when they become confused, how context and demonstration support comprehension, and what happens when instructions are difficult to follow.

The experience is particularly relevant to EBC’s emphasis on teaching English through English. When trainees themselves become beginners in an unfamiliar language, they can experience first-hand why a teacher needs to communicate clearly, provide context and check understanding rather than assume that learners have followed an explanation.

What trainees learn from the Unknown Foreign Language experience

The value of the unit is not simply that trainees spend four hours learning a new language. It is that they have an opportunity to examine the learning experience from the student’s perspective and consider how it should inform their own teaching.

During the lessons, trainees may reflect on several questions:

• How does the teacher communicate meaning without translating into a language the trainees understand?
• Which gestures, pictures, demonstrations and examples make unfamiliar language easier to understand?
• How does the teacher show learners what to do when instructions are given in an unfamiliar language?
• What happens when the teacher speaks too quickly or introduces too much unfamiliar language at once?
• How do learners feel when they understand an activity, make progress or struggle to follow the lesson?
• Which teaching techniques would be useful when teaching English to learners who do not share the teacher’s first language?

These observations can help trainees connect classroom techniques with the experience of learning. A demonstration that initially seems like a simple teaching tool may become much more valuable when a trainee has personally depended on it to understand an unfamiliar task.

The experience can also encourage trainees to think about the difference between a teacher knowing what they mean and a learner actually understanding the message. Clear intentions do not guarantee clear communication; teachers need to observe learners’ responses and adapt their approach when necessary.

The trainee learning journal

After the Unknown Foreign Language lessons, trainees are required to write a journal reflecting on their experiences and identifying key points they intend to apply when teaching English to English language learners (ELLs).

This reflective task helps trainees move beyond describing what happened during the lessons. They are expected to consider what they learned about language teaching and how that learning could influence their own classroom practice.

For example, a trainee might reflect on how a demonstration helped them understand an instruction that they could not follow from the spoken language alone. They could then explain how they would use demonstrations when setting up a speaking activity in an English lesson.

Another trainee might observe that they became confused when too many unfamiliar words were introduced at once. They could use that observation to plan shorter instructions, introduce key vocabulary in context or provide visual support when teaching English.

A trainee might also reflect on the emotional experience of not understanding everything. This could inform how they respond to learners who hesitate, make mistakes or need more time to process instructions.

The journal therefore connects personal experience with professional development. Trainees are encouraged to identify practical techniques, explain why they may be useful and consider how they will incorporate them into their own teaching.

Connecting the unit with Krashen’s hypotheses

The Unknown Foreign Language unit has several useful connections with Krashen’s theory, particularly the Input Hypothesis and the Affective Filter Hypothesis.

Comprehensible input: Trainees experience the challenge of understanding a language they do not speak. They can observe how context, demonstration, repetition, gestures and other forms of support make the teacher’s language easier to follow. This connects with Krashen’s emphasis on understanding messages as part of language acquisition.

The affective filter: Trainees may experience uncertainty, frustration, curiosity, confidence or satisfaction as they participate in the lessons. Reflecting on these responses can help them appreciate why classroom atmosphere, encouragement and appropriately supported tasks matter to learners.

Acquisition and learning: Trainees can consider the difference between understanding and using language in activities and consciously analysing its rules. Their experience may prompt them to reflect on the place of meaningful communication and explicit explanation in their future lessons.

These connections should be understood as opportunities for reflection rather than proof that Krashen’s hypotheses explain every aspect of the experience. The Unknown Foreign Language unit is a teacher-training activity, and its educational value lies in helping trainees observe, analyse and reflect on language-learning processes.

Why the experience matters when teaching English through English

EBC trains its teachers to conduct lessons in English and not to use the learners’ native or local language during teaching practice. If trainees use the local language while teaching, this may be raised during trainer feedback as an area for improvement.

The Unknown Foreign Language unit provides a complementary perspective. While teaching practice develops trainees’ ability to teach through English, the language-learning experience gives them an opportunity to understand some of the challenges that learners may face when they do not understand the language being used.

Together, these experiences encourage trainees to develop alternatives to translation. They learn to consider how they can demonstrate meaning, adapt their language, use visual support and check comprehension while keeping classroom communication in the target language.

The objective is not merely to avoid using the learners’ native language. It is to develop the ability to teach effectively without depending on it. An English-only lesson still needs to be comprehensible, well structured and responsive to the learners’ needs.

The unit also encourages reflective practice. By documenting their experiences and identifying techniques they intend to use in their own teaching, trainees can turn a short period of language learning into a source of practical professional insight.

The role of grammar in Krashen’s view

Krashen distinguished between acquiring a language through meaningful exposure and communication and learning about a language through the conscious study of rules. In his view, consciously learned grammar knowledge can act as a monitor, helping learners check or edit their language when they have sufficient time, are focused on accuracy and know the relevant rules.

Krashen did not argue that grammar has no educational value. Rather, he questioned whether the conscious study of grammar alone is sufficient to develop fluent communicative ability. He also emphasised the importance of understanding messages and receiving comprehensible input.

For teachers, this distinction raises a practical question: how can lessons combine meaningful communication and comprehensible language with appropriate opportunities to notice, practise and understand grammatical forms?

One approach is to integrate grammar into communicative activities. A lesson on the present perfect, for example, might include a brief explanation of the form, followed by a class survey in which learners ask one another about life experiences. The teacher can then provide feedback on recurring errors and offer further practice where necessary.

This approach does not require teachers to choose between communication and grammar instruction. Instead, it encourages them to consider how explicit explanations, guided practice and meaningful language use can complement one another.

For trainees learning to teach English through English, grammar presentation also provides an opportunity to practise explaining language clearly without relying on translation. Examples, timelines, concept-checking questions and carefully staged activities can help learners understand both the form and meaning of a structure.

Teaching English without relying on the learners’ native language

Teaching English through English does not mean using English that learners cannot understand. On the contrary, it places greater responsibility on the teacher to make the language comprehensible.

When a teacher cannot rely on translation, lesson planning and classroom communication become particularly important. Teachers need to consider the vocabulary they use in instructions, the length and complexity of their explanations, the examples they provide and the support learners may need to follow an activity.

Several techniques can help teachers communicate meaning effectively:

• Visual aids: pictures, diagrams, flashcards and written examples can clarify meaning.
• Gestures and demonstrations: teachers can show learners what a word means or how an activity should be completed.
• Contextualisation: introducing vocabulary and grammar through a situation, story or conversation helps learners connect form and meaning.
• Graded language: teachers can adapt their vocabulary, sentence length, speed and explanations to the learners’ level.
• Concept-checking questions: carefully designed questions help teachers establish whether learners have understood a word, structure or instruction.
• Examples and modelling: showing learners what a successful answer or completed activity looks like can reduce confusion.
• Elicitation: asking guided questions can help learners work out meaning or language patterns rather than simply receiving an explanation.

These techniques support comprehension while keeping the lesson focused on English. They also help teachers develop a wider range of classroom skills instead of depending on a single method of explanation.

An English-only approach does not automatically guarantee a successful lesson. If the teacher speaks too quickly, uses unnecessarily complex language or fails to check comprehension, learners may struggle even though the entire lesson is conducted in English.

The aim is therefore not simply to maximise the amount of English spoken by the teacher. It is to use English purposefully and at a level that gives learners a realistic opportunity to understand and participate.

How EBC trains teachers to teach through English

At EBC, trainees are trained to teach English through English. They are expected to avoid using the learners’ native or local language during their teaching practice and to develop techniques for communicating meaning directly in English.

This expectation is reinforced through practical teaching sessions and trainer feedback. Trainers observe how trainees present language, give instructions, explain vocabulary, manage classroom activities and check learners’ understanding. If a trainee uses the local language during a lesson, this may be raised during the feedback session as an area for improvement.

The purpose is to help trainees develop the practical competence needed to conduct an English-language lesson without depending on translation. Rather than simply being told not to use the learners’ native language, trainees need to learn alternative ways to make meaning clear.

For example, a trainer may encourage a trainee to replace a translation with a visual aid, demonstrate a task instead of explaining it at length, simplify an instruction or use concept-checking questions to establish whether learners understand.

Feedback gives trainees an opportunity to reflect on their decisions and try more effective techniques in subsequent lessons. Over time, this practice can help them become more confident in using English to manage a classroom, present language and support learners with different levels of proficiency.

The Unknown Foreign Language unit complements this process by allowing trainees to experience language learning from the student’s perspective. The lessons and subsequent journal encourage them to identify how teaching techniques affect comprehension and how they can apply these insights to their own English lessons.

This practical focus is an important distinction between learning about teaching methodology and developing the ability to apply it. Understanding theory is useful, but teachers also need to practise classroom techniques, evaluate their effectiveness and respond to feedback.

Limitations and criticisms of Krashen’s theory

Krashen’s hypotheses have been influential, but they have also attracted criticism and debate. One important issue is how clearly acquisition can be separated from conscious learning. In real classrooms, learners may draw on implicit knowledge, explicit rules, feedback and interaction at the same time.

The Input Hypothesis has also prompted discussion about whether comprehensible input alone adequately explains language development. Interaction with other speakers, opportunities to produce language, feedback and attention to form may also contribute to learning. Teachers therefore should not interpret the hypothesis as meaning that speaking practice, grammar instruction or correction is unnecessary.

Another consideration is that language learners differ considerably. The input that one learner finds accessible may be too difficult or too easy for another. Motivation, anxiety and confidence can also vary according to the learner, the task and the learning environment.

Similarly, the fact that a lesson is conducted entirely in English does not automatically mean that learners understand it. Teachers need to monitor comprehension and adapt their language and teaching techniques accordingly. This is why practical skills such as demonstration, contextualisation, grading language and concept checking are important in an English-only teaching approach.

Krashen’s hypotheses should therefore be understood as an influential theoretical perspective rather than a complete explanation of every process involved in second-language acquisition.

For teachers, the value of the model lies partly in the questions it encourages: Are learners able to understand the language they encounter? Do they have opportunities to communicate meaningfully? Are grammar explanations supporting their learning goals? Does the classroom environment encourage participation? Are teachers checking comprehension rather than assuming that learners understand?

These questions can inform lesson planning and professional development, including the practical training and reflective activities that form part of EBC’s approach.

Video: Stephen Krashen’s theory of second language acquisition

The following video provides additional context for understanding second-language acquisition and Krashen’s ideas.

Watch the video on Youtube.

Train to teach English through English with EBC

Understanding second-language acquisition theory can help aspiring teachers make informed decisions about classroom practice. However, becoming an effective English-language teacher also requires practical skills: presenting language clearly, giving instructions, managing activities, checking comprehension and responding to learners’ needs.

At EBC, trainees practise teaching English through English and receive feedback from trainers on their classroom performance. They develop techniques for explaining vocabulary and grammar, demonstrating activities and supporting comprehension without relying on the learners’ native language.

The Trinity CertTESOL Unknown Foreign Language unit adds another dimension to this preparation. By participating in four hours of lessons in an unfamiliar language and reflecting on the experience in a learning journal, trainees can examine language learning from the student’s perspective and identify practical techniques to use in their own classrooms.

Together, teaching practice, trainer feedback and reflective learning help trainees connect teaching methodology with classroom experience. They provide opportunities to develop not only an understanding of language teaching but also the practical judgement needed to make English comprehensible to learners.

Krashen’s emphasis on comprehensible input provides one useful perspective for understanding why clarity and meaningful exposure matter. EBC’s training approach turns these broader teaching considerations into practical skills that trainees can develop and apply.

If you are considering a career in English-language teaching, explore EBC’s TEFL training courses to learn more about the training available and how practical teaching experience can help you prepare for the classroom.

Conclusion

Stephen Krashen’s Monitor Model has played an important role in discussions of second-language acquisition and language teaching. Its five hypotheses draw attention to the proposed distinction between acquisition and conscious learning, patterns in grammatical development, the role of conscious monitoring, comprehensible input and the influence of affective factors.

For English-language teachers, these ideas provide a useful starting point for reflecting on classroom practice. They encourage teachers to consider how learners encounter language, how they develop communicative ability and how classroom conditions may affect participation and engagement.

Krashen’s emphasis on comprehensible input is particularly relevant when considering how teachers can communicate effectively in English without depending on translation. At EBC, trainees develop this ability through practical teaching experience, trainer observation and feedback. The Trinity CertTESOL Unknown Foreign Language unit complements this training by placing trainees in the position of learners for four hours of instruction in a language they do not speak. Their subsequent journals encourage them to reflect on the experience and identify techniques they can use when teaching English to ELLs.

These activities help trainees connect theory with practice. They can learn to make meaning clear through demonstrations, contextualisation, visual support and concept-checking questions, while recognising the importance of adapting their teaching to learners’ needs.

At the same time, Krashen’s hypotheses should be considered alongside other perspectives on language learning, including the roles of interaction, feedback, explicit instruction and individual differences. No single theory fully accounts for the complexity of how people learn an additional language, and teaching in English requires more than simply avoiding the learners’ native language.

Understanding Krashen’s ideas, combined with practical training and reflective teaching, can help teachers make informed decisions about how they present language, support communication and respond to learners’ needs. The ultimate aim is to create learning experiences that combine meaningful language use, appropriate guidance and opportunities for learners to develop both fluency and accuracy.

Accuracy note: The article distinguishes Krashen’s five hypotheses from EBC’s and Trinity’s specific training policy. The Unknown Foreign Language unit is presented as an opportunity for experiential learning and reflection, not as proof that Krashen’s theory requires an English-only classroom.

Disclaimer: EBC’s discussion of Stephen Krashen’s theories is for educational purposes only. Although EBC incorporates selected principles associated with Krashen’s work into its approach to English-language teacher training, this does not imply that Stephen Krashen endorses, sponsors or is affiliated with EBC or its courses. EBC is independently operated, and its training approach reflects its own educational principles, practices, and decision to include some of Dr Krashen’s excellent work.