What sounds more natural the big red dog or the red big dog? It’s likely that you chose the big red dog, but could you explain how do you know? Can you explain the exact complex grammatical structures and rules for the ordering of those words? The answer is probably no, but yet you able to decipher between these 2 phrases. This is all because of your mind’s intuition, it has been trained thorough via input. Input referring to listening and reading in a language, and as children we are trained through thousands upon thousands of inputs from parents and our surrounding environments. With this input, the mental model of the language gradually but steadily begins to develop. Therefore it is vital for individuals to gain massive amounts of input.
In Stephen Krashen comprehensible input hypothesis, aka the i+1 formula, he describes how language is best acquired. When a child understands a conveyed message, comprehensible input, they will learn and comprehend the message in the future. However to learn, the concept of "i+i" refers to input requiring to be one level above (+1) the learner’s current level of language (i). Meaning ideally input shouldn’t be too hard nor too easy, but instead just in between to improve. Compare it to weight lifting, it’s improbable that someone can lift an extremely heavy bar of 200 lb, but if they started lifting off with something smaller like 50 lbs, and incrementally increase difficulty overtime, the 200 lb bar will be liftable.
Moreover people understand new messages through context and other external factors. For example, Felipe is a miser. He’s always been a cheapskate.(*1)
Eventually, countless hours of input trains the intuition; then an individual can take a message and mentally compare them through the large selection of previous input (database) if said messages matches with the database. Hence you are able to “feel” if something is unnatural sounding or tell the difference between an American and British accent. No one verbally informs children and us the complex patterns involved. We may not consciously know the grammar rules, but “we just know.”
To emulate how babies acquire language, listening and reading their surrounding environment, the natural course of action is to mirror said way of learning. Therefore, masses of input should be acquired historically; gaining masses of input in the target language was difficult since there were no accessible ways of gaining input anywhere, anytime, reliably, affordably, consistently, etc. Unless they’re in the target language’s country, which is the most ideal option. However with advent of the internet, there’s an infinite selection of native content, videos, books, and audio feasibly accessible to anyone in the world. Not only that but native speakers are readily available on forums, chatrooms, and calls. This approach is called “Immersion,” immersing oneself within the target language.
Additionally immersion, specifically self-study immersion, has many advantages compared to traditional language learning. Mainly that immersion will be considerably more enjoyable since you can select what content you consume, thus it is relevant and fun to you as an individual. For example, if I immerse in fantasy games on Youtube related words like mana, wizard, health points, etc will be learned up. I also enjoy fantasy games so it will boost my interest, subsequently boost acquisition in the language. The importance of interest is extremely underemphasized in traditional teaching, to learn a language requires thousands of hours of input and time spent outside the classroom, to push through those lengths of time it requires motivation so interest is used to help. Boredom is public enemy #1 when it comes to learning.
Another advantage to content from immersion is that it is “by natives for natives,” so grammar, diction, etc will be natural sounding since that’s how actual natives speak. Picking up the small details from natives is vital, since your native language culturally differs from your target language, especially if it’s literally across the world (eg. English vs Chinese). Details from natives in word choice, word definitions, word use-cases, grammar, speech, stress accent, and registers (formality scale) in language are very complex and they can only be picked up through training of the intuition. Conscious knowledge won’t suffice, you need to know quickly, effortlessly, and consistently. Trying to consciously create language like a math equation is problematic, and there in lies the fundamental issue with traditional language teaching.