A Stressful ShakingI was taping a talk when it started. The room began to shake. I’ve been in many earthquakes, but this one was different. It started slowly, and it got bigger, louder, and meaner. I froze. "This is bad," I said to myself. I knew it was time to "move to safety." I turned off the camera, opened the door, and stood under the door jam.By now everything in my office was jumping, flying, rolling, and falling. The whole building shook like a dog that had just left the water. When it finally stopped, I felt lucky to be alive. Then I thought, "Oh, no! I turned off my camera. I guess my "stress" blocked my ability to get "input" in my camera, so I could really see and "understand" what happened.This story shows how stress affects us. In the 1970’s, Dr. Stephen Krashen developed a set of 5 theories, which emphasized "input" and "lowering stress." Krashen challenged skills, drills, and grammar-oriented language teaching. Today, critics claim Krashen over-emphasizes input, but his "input hypothesis" remains important. And some might say that Krashen helped to revolutionize language teaching. Because of Krashen, teachers focused less on language, grammar, and rules, and they focused more on messages.Learning Versus AcquisitionKrashen explains his ideas through five basic theories. First, he emphasized the difference between learning and acquisition. Learning is a conscious process, when we learn, we study about language and rules. For example, we study and learn this rule: "For the past tense, add -ed to the end of regular verbs." When language is learned, we think, "I live (oh yeah, I need to add -ed for the past)… I lived in Seattle." That is, with learning, we think about the rule, and then we use it.But when we acquire language, we don't need to think about grammar rules. We can say things automatically. With acquisition, we have a feel for the language. We can produce correct sentences automatically. We use the rules of grammar correctly — without thinking about them. If teachers believe the acquisition/learning hypothesis, they might deemphasize grammar teaching. But we still need to ask: How can we teach language so that students acquire it and can use it automatically?The Natural OrderSecond, Krashen emphasizes the idea that we acquire language in a natural order. For example, first language learners acquire the progressive -ing rule early. "I'm going to play a game." Then about 6 months to a year later, these learners will acquire the third person singular rule: "I think John likes Mary."But before that, these learners might say: "I think John like Mary." If the natural order hypothesis is true, students might not acquire some rules if they are not ready for them. The natural order also reminds us that teachers can teach too much. And as we will see below, Krashen's answer is giving students more input.The Editor and the MonitorThird, Krashen talks about the monitor hypothesis. The monitor is like an editor. When we are not sure that a sentence is correct, we ask an editor to help us. The editor remembers the rule, and she corrects the sentence. Where is the monitor/editor? She is in our brains. She is the part of our brains that knows grammar, spelling, and punctuation rules.With the monitor hypothesis, we see how learning versus acquisition actually works in the brain. For Krashen, we sometimes need the monitor, but she doesn't really help us acquire language. In fact, when we monitor our grammar while speaking, we probably produce less language and speak less fluently.The Centrality of InputFourth, Krashen brings us his input hypothesis. The input hypothesis is the central and most important part of his work. We can summarize the input hypothesis very simply: We acquire language by understanding messages. There are two key phrases: "acquire language" and "understand messages."By understanding lots of messages, we can acquire language automatically. For Krashen, the input hypothesis solves the problems of the first three theories. With lots of input, we don't learn language, we acquire it. With lots of input, we acquire language in its natural order. With lots of input, we acquire language so that we will need the monitor less.Emotions, Motivation, and AffectLastly, Krashen gives us the affective filter hypothesis. Krashen cares most about input. But what if we have a filter that stops input from coming into our brains. For Krashen, this filter relates to emotions, motivation, and self-esteem. Sometimes students have negative emotions about their teacher or the books they read.These negative emotions will block input, like a filter. If a student lacks motivation, this will block input. If a student has low self-esteem, if he doesn't believe in himself, then this will stop input, like a filter. For teachers, this means we need to create classrooms with positive emotions and powerful motivation. And we need to inspire students to believe that they can acquire language.So What?Krashen changed language education. He caused many teachers to focus more on communication and messages — and less on grammar and language rules. But Krashen has his critics. Many scholars have written a lot of words "bashing Krashen." What about you? Which of these theories make the most sense? Which of these theories sound funny to you? Which are supported by evidence? Which lack support? Which can you use as a teacher and learner?