The methods of teaching a world language stem from the most current studies of Second Language Acquisition, which have changed vastly over the past fifty years.  Before the work of language theorist, Stephen Krashen, the world language classroom was instructed in a rather rote manner.  Student learning was dependent on the memorization of long vocabulary lists in isolation, as well as the completion of specific grammar drills.  Everything was done in a very specific order, and students simply could not advance on to the next skill until they had mastered the first.  For example, teachers believed that students could not handle the use of the past tense in the language until they were able to produce the present tense, which is not realistic when we think about the communicative necessities we need to get a message across. While many students felt accomplished when they memorized a certain list or perfected a grammar skill, their ability to actually communicate in the language fell flat--leaving many teachers to hear the dreaded quote, "I took four years of Spanish in  high school and all I know how to do is ask to use the bathroom!"

   Stephen Krashen, a linguist and educational researcher at the University of Southern California, believed the focus of the traditional classroom lied too heavily in what students were able to produce without giving them the proper exposure to the language structures first.  After recognizing these shortcomings, Krashen began to develop his own theory of Second Language Acquisition in 1972.  As a Spanish teacher, it is very important to me as a professional to be able to teach my students in the most effective and efficient ways possible. This work will take a look at the thought process behind Krashen's theory and examine how each concept presented can be utilized within the modern world language classroom.

 The fundamental building block of Krashen's Theory is the Acquisition-Learning Hypothesis. This hypothesis is fundamental to Krashen's Theory as a whole, as it states the two different ways that adults are able to develop competence in a second language. Krashen was able to distinguish himself from other language theorists with the idea that language is acquired and not learned.  Krashen delved deeper in what separates the idea of learning from acquisition within two systems called the "Learning System" and the "Acquired System".  

The Acquired System is very similar, if not identical, to the way in which children develop their first language.  The Acquired System refers to the unconscious assimilation of learners to the language. This system later leads to the ability of learners to interact and communicate with native speakers of a language. Learners start by being exposed to meaningful language repeatedly over a period of time. After a certain amount of exposure, students acquire this meaningful language, and can in turn produce it when they need to. The Acquired System allows for learners to successfully communicate a message.

The Learning System refers to a learner's conscious knowledge about the language.  This means that rules are explicitly taught and learned through memorization.  The Learning System can be used to learn grammatical concepts, and to rationalize why language is used in certain ways.  While this system takes a higher level of metacognition of the language, it is not necessary to master these skills in order to communicate effectively within the language. 

The Learning System can also falter when it comes to the fluidity of language over time, dialects, and generations.  Language cannot be deduced to simply one set of rules, as it is irregular and ever-changing. In this case, it is best for learners to be exposed to authentic language usage, and not just the formula for a correct sentence.

If we look at a new learner of a language, the Acquired System is certainly more important, as you cannot develop knowledge about the language until you have acquired the language. The process of the Acquired System is what most closely mimics how children learn their native language, as learners are unconsciously exposed to meaningful language. 

In the Natural Order Hypothesis, Krashen discovers that language learning occurs in a predictable order amongst learners. Within a certain language, there are specific grammatical structures that are learned more quickly than others. 

This has changed the way that World Language Teachers have framed their currriculum, as the Natural Order of language acquisition develops independently from the order of a textbook.

The Monitor Hypothesis is an extension of the Acquisition-Learning Hypothesis, as it seeks to explain the relation of learning and acquiring a language to the second language acquisition process. According to Krashen, "Conscious learning is available only as a 'monitor' which can alter the output of the acquired system before or after the utterance is usually spoken or written" (Krashen, 16).

To put it more simply, language learners have the language that they have learned (explicit teaching that requires recall to produce), and language that they have acquired (structures that have been repeated multiple times in several different meaningful contexts).  When it comes time for a student to produce the language, they will most easily produce the language that they have already acquired.  Students tend to struggle with producing learned language, as they need to "monitor" themselves before or after it is produced. In many cases, the "monitor" tends to hold students back.

The Monitor Hypothesis states that the conscious learning of grammatical rules and structures plays a limited part in second language acquisition.  There are three strict conditions that learners have to meet in order for conscious learning to function as intended.  According to Krashen, these conditions are time, a focus on form, and knowing the rule.

• Time:  In order for conscious learning to function as intended, learners need time to be able to think about the rules that they have been taught.  The issue with this is that learners generally do not have the time to think about rules when they are having real-life conversations, and therefore the grammatical rules they have learned go out the window.  
• Focus on form: Even if students are given time, they need to be focused on the language forms that they are using.  Most lower level learners struggle with this, as they have had very little exposure to the language to know if the forms they are using are actually correct.
• Know the Rule: This constraint is detrimental to most learners, as language is extremely complex and fluid over time.  Even native speakers struggle to know why they speak in a certain way.

The Input Hypothesis is the theory that Krashen considers most important within his works, as it attempts to explain how humans acquire a language. 

Input is anything that the learner hears or reads within the target language, whereas output is what learners are able to produce.  Krashen believes that in order for learners to acquire language, they need to be exposed repeatedly to comprehensible input, or meaningful language that they can understand.  The video below shows examples of comprehensible input.

Not only do we need to hear and read comprehensible input, we need to be exposed to these structures multiple times in several different contexts in order to acquire the language.  In addition, Krashen believes that if we want to advance to a higher language level, we need to be exposed to a sprinkling of input that is slightly higher than our current level.  He calls this theory "i+1"-- "i" being our current level, and 1 being the next step.  "We acquire...only when we understand language that contains structure that is "a little beyond" where we are now" (Krashen, 21). Krashen says that we use extra linguistic information as well as context in order to understand language that is one step further than current knowledge. 

Krashen's Theory of "i+1" has a lot of similarities to Lev Vygotsky's Zone of Proximal Development, which states that learners can learn when given added assistance to what they already know.

The Affective Filter Hypothesis reflects on how student disposition can impact language acquisition.  Krashen believes that there are three affective variables that affect successful language acquisition:

• Motivation- Learners with high motivation tend to have more success in language acquisition. 
• Self-confidence- Learners with high self-confidence tend to be more successful in language acquisition. 
• Anxiety- Language acquisition best occurs when anxiety is low in the classroom setting.

"The "affective filter", posited by Dulay and Burt (1977), acts to prevent input from being used for language acquisition. Acquirers with optimal attitudes (see text) are hypothesized to have "low" affective filters. Classrooms that encourage low filters are those that promote low anxiety among students, that keep students "off the defensive" (Stevick, 1976)." (Krashen, 32). 

Krashen reflects that the pressure of teacher grammatical rules and drills tends to raise anxiety in the classroom, whereas providing students with simple and comprehensible input in an engaging way helps to keep students motivated with low amounts of anxiety.

 Through the teachings of Krashen, several language teachers have implemented their own methods of instruction.  One of the most popular current forms of teaching is TPRS (Total Physical Response and Storytelling), which was created by Blaine Ray in the late 1980's.  TPRS stories are repetitive and provide language in a meaningful, contextual way.  TPRS focuses on keeping students interactive and engaged in a low-anxiety manner, which is exactly what Krashen teaches within his five hypotheses.  In the first five minutes of the video below, you will see how TPRS works in a first year Spanish class.

TPRS is so effective because it provides several exposures to language structures in different contexts, which is what Krashen emphasizes throughout his theory.  The story aspect of the practice keeps the language engaging and relevant.  Krashen acknowledges that comprehensible input is great, but if students are not interested in or paying attention to the language being provided to them, they will not acquire any language. 

   While Krashen's theories are widely accepted amongst the World Language community, there are several critiques of his hypotheses.  The most important critique that Krashen faces is a lack of quantifiable evidence or data to support his claims.  Language theorists Lightbown and Spada question whether or not these hypotheses could be supported by empirical data (Lightbown & Spada, 2006, p.38).

  More specifically, when we look at the theory of "i+1" within the Input Hypothesis, Krashen discusses "i" as students' current language level, and "1" being one step above that level.  The issue with this hypothesis is that as teachers, we are not able to quantify exactly what a student's current language level is, nor can we necessarily say what is "1" step above it.  This makes it difficult to decide what input is "comprehensible" for students, and even if we could, it is possible that it would vary from student to student, and therefore would not be comprehensible to all. 

  While these critiques are valid, as a level 1 teacher, for students who have never taken Spanish, I can make language as comprehensible as possible by providing visual support for whatever I am saying, as well as using as many cognates (words that look the same in Spanish and English) as possible.  If I am making the language comprehensible for my lower level learners, then the higher level learners will certainly still benefit from the repetitions of language structures.  Even though these theories are not quantifiable, I have notice that students receive way more exposure to the language (as they would if they went abroad) than they would have in a traditional classroom, in which they would only receive isolated vocabulary structures not in context. 

As a Spanish teacher who regularly utilizes TPRS in her classroom, the teachings of Krashen have had a huge impact upon my professional career.  Through the five hypotheses, I have learned to always use comprehensible input in a low-stress environment for students.  I, along with my colleagues, have moved away from the constant grammar rules as a guideline to how students learn.  Stephen Krashen and his Theory of Second Language Acquisition have changed and continue to change the modern World Language Classroom.

ALLWRIGHT, R. (1975) Problems in the study of the language teacher's treatment of error. In M. Burt and H. Dulay (Eds.) New Directions in Second Language Learning, Teaching, and Bilingual Education. Washington D.C., TESOL.

KRASHEN, S. (1981) Second Language Acquisition and Second Language Learning. Oxford: Pergamon Press.

KRASHEN, S., HOUCK, N., GIUNCHI, P, BODE, S., BIRNBAUM, R. and STREI, J. (1977) Difficulty order for grammatical morphemes for adult second language performers using free speech. TESOL Quarterly 11: 338-341.

KRASHEN, S., ZELINSKI, S., JONES, C. and USPRICH, C. (1978) How important is instruction? English Language Teaching Journal 32: 257-261.