In this article, we present an example of learning based on grammar rules. Then we explain why we think this way of learning is much less effective than input-based learning.
Here is an excerpt from a modern ESL textbook ("Workout Advanced" by Paul Radley and Kathy Burke, published by Nelson English Language Teaching). The textbook was used in an English class Tom attended at a language school in England.
Unit 4. Grammar: Adjectives
When two or more adjectives are used before a noun, the adjectives follow a certain order:
opinion adjectives: general/specific
descriptive adjectives: size/age/shape/colour/nationality/material
Example: They bought a lovely, stylish, large, old, rectangular, brown, English oak table.
Unit 4. Practice (next page)
Use the adjectives in the correct order before each noun to make noun phrases.
beach — white, sandy, soft --> a soft, white, sandy beach
The textbook presents a grammar rule for ordering adjectives ("size/age/shape/colour/nationality/material"). Then it gives only two examples. After that, you are expected to do an exercise.
Obviously, you cannot do the exercise using your intuition (what intuition can you get from seeing only two examples?). The textbook wants you to use the grammar rule. You are supposed to classify the adjectives into one of the groups ("size", "age", etc.), and then put them in order according to the rule. In other words, you are supposed to:
Now imagine doing all these things whenever you're writing or saying a sentence with 2 or more adjectives. Can you guess how much time it would take you to build the sentence?
Is there another way? Yes, there is. You can learn by input. You can read a lot of sentences with adjectives and get a natural, intuitive knowledge of adjective order. Instead of memorizing the rule and using it to build sentences, you can get correct sentences into your head and your brain will imitate them. The "input way" is easier and it lets you speak and write faster.
Of course, learning by input is not effortless. You have to spend a lot of time reading and listening to English. However, if you learn e.g. by reading a book that you like, it can give you pleasure and motivation.
Learning with grammar rules has two important disadvantages:
Yes, they can. For example, if you don't hear (or read) some word or grammar pattern frequently, it may be hard to acquire a natural, intuitive knowledge of it. For example, it may be hard to acquire an intuitive knowledge of the future perfect tense (a grammar structure used e.g. in this sentence: "By 2050, life in Europe will have changed.") just by reading books in English, because the future perfect occurs relatively rarely in books.
If you want to use the future perfect in your own sentences, you can memorize a rule for it. The rule will tell you when to use the future perfect and how to use it correctly. In a similar way, you can memorize other rules or definitions of words which are used rarely.
So you could substitute grammar rules for intuition. The problem with this method is that you can't remember too many rules (memory limit). Also, it would slow you down if you had to use many rules when speaking or writing (time limit). Therefore, most of your knowledge must be intuitive (based on input).
Grammar rules may be useful for using rare words and grammar patterns, but we think there is a better way. You can build your intuition "the input way" for every rare grammar pattern. How? You can artificially increase the frequency with which you see that grammar pattern. For example, if you don't see the future perfect often, you can add 20 example sentences with the future perfect to your SuperMemo collection. SuperMemo will make you repeat the sentences regularly, and so will help you to build an intuitive knowledge of the future perfect.
Many learners have a strange habit. When somebody (e.g. a teacher) tells them the correct way to say something in English ("We say big red car.") or corrects their mistake ("You can't say red big car"), they like to ask "why?".
However, the question "why?" has no real answer. When asking the question, learners want to hear a grammar rule (e.g. "We say big red car because adjectives of size come before adjectives of color"). But the rule is not the reason why we don't say "red big car". The rule is only a description of native speakers' habits. It was invented by some linguist who simply noticed that native speakers never say "red big car" or "white small house".
In other words, it is not true that native speakers say "big red car" because they know the rule and follow it. It's the other way around. The size-color rule exists because native speakers say "big red car". Native speakers are the ones who create the language. Grammar rules only follow native speakers' habits.
We think that it doesn't make much sense to ask the question "why is that sentence correct, and not the other one?". The only good answer to that question would be "Because native speakers say that sentence, and not the other one.". Instead of wondering "why?", simply learn the correct way. You don't have to care that a linguist wrote a rule for it. Follow native speakers, not grammar rules