More teachers are discovering the joy of teaching with comprehensible input-based methods like TPRS. To effectively implement the WHAT and the HOW of these methods, understanding the WHY is crucial. Dr. Stephen Krashen’s Hypotheses of Language Acquisition are the why.

In this series of posts we will explore each of Krashen’s major hypotheses and how they apply in the classroom. Krashen’s is not the only model of learning teachers need to know, but due to their enormous influence, it is crucial that modern language teachers understand these hypotheses and how they apply in the classroom.

This is the same series of lessons I teach to my students to help them understand why I teach the way I do so they can cooperate fully and get the most out our time together.

The next post in this series (#2/9), which describes the first of Krashen’s Hypotheses, The Monitor Hypothesis, is found here.


“Language acquisition does not require extensive use of

conscious grammatical rules, and does not require tedious drill.”

─Stephen Krashen, PhD, Principles and Practice in Second Language Acquisition (1982)

“The overwhelming number of teachers are unable to name

or describe a theory of learning that underlies what they do.”

─Alfie Kohn, Punished by Rewards (1993)


What Do You Already Know ?                       

• What is the most influential of Krashen’s hypotheses of language acquisition?

• What are Krashen’s 6 main hypotheses of language acquisition?

• How are these hypotheses different from the assumptions about language learning in a traditional classroom?

• How do instructors apply Krashen’s hypotheses in the classroom?


To say that Stephen Krashen’s hypotheses of second language acquisition (1982, 2011) have had an influence on the way teachers think about language teaching is an understatement. Krashen’s work has revolutionized teaching practice in language classes by shifting the focus from a grammatical syllabus to a model of language learning that focuses on comprehensible input. His first five hypotheses, formulated in 1982, have stood the test of time over the last 30+ years and are supported by scores of studies supporting comprehensible input-based teaching.

But change comes slowly. Traditional teaching methods are often grounded in nostalgia rather than research and change happens at a glacial pace. Even when teachers set out to use new methods the multiple demands of the classroom and school culture can cause even well-intentioned teachers to revert to the way they were taught and progress stalls.

Krashen’s hypotheses go against some aspects of conventional thinking. Academic peer pressure and tradition help to maintain the status quo. In order to overcome educational inertia and to apply this research-based understanding of SLA in the classroom a teacher may need to focus like a maniac.

As a mnemonic device, Krashen’s hypotheses can be arranged to form the acronym MANIAC:

  1. M = The Monitor Hypothesis
  2. A = The Acquisition/Learning Hypothesis
  3. N = The Natural Order of Acquisition Hypothesis
  4.  I = The Input Hypothesis
  5. A = The Affective Filter Hypothesis
  6. C = The Compelling Input Hypothesis (2011)


If this mnemonic does not seem respectful or serious enough to you, think about rearranging the letters like this when you present them to your students:

A CI MAN” (an apt description of Dr. Krashen, the original C.I. man), “CAIMAN” (a South American crocodile, an exotic and interesting animal), or “CAMINA” (walks, in Spanish, which is appropriate as we stroll through some of the most important hypotheses in world education in the last 40 years.)

The next post in this series (#2/9), which describes the first of Krashen’s Hypotheses, The Monitor Hypothesis, is found here.
NOTE: This is a series of short posts on Stephen Krashen’s 6 main hypotheses of language acquisition, presented in a simple form. I teach these ideas in this same way to my high school students. We even have quizzes on each of the hypotheses. It helps students to know something about linguistics so that they understand WHY certain methods are being used in class—that the teacher is not just making up activities, that what is being done in the classroom has a basis in theory, research, and successful practice. I also want to prepare them to be able to identify best practices in language courses they may take later.
We use the acronym MANIAC to remember the 6 hypotheses and because a teacher may need to focus like a maniac in order not to be swayed by the inertia and tradition in education. Don’t worry about the “maniac” moniker, you’ll get maniacal energy from your engaged and acquiring students once you learn how to put these hypotheses into action.