If you ask “How can I learn to speak English better?”, many people will tell you “Practice, practice, practice”. “Speak and write in English whenever you can”, they’ll say. All English classes are full of activities which involve speaking and writing. You produce sentences when you do an exercise in your textbook, when your teacher makes you speak in class, or when you have to write a composition. All these activities are supposed to help you with your English.
Practice can be very useful. It’s even necessary to learn English well. So what’s the problem? The problem is that for many learners, speaking or writing means making a lot of mistakes. Some people make a mistake in every sentence!
Suppose you are writing an e-mail message in English. Your English is not perfect and you want to write the message quickly. You write (incorrectly): I want speak English.
When you write a sentence, you also read it. So the incorrect sentence becomes “toxic input” for your brain. The next time you write a message, you will be more likely to write I want finish or I want be happy. Why? Because I want speak English is fresh in your head — you recently used it! And when you write I want a few more times, you’ll get a bad habit: I want will become your natural way of speaking English. Such bad habits can be very difficult to eliminate. Even if somebody later points out your mistake and you concentrate very hard to avoid making it again, the bad habit is often stronger. It’s an uphill battle.
Every time you write or speak with mistakes, you reinforce those mistakes. As you repeat your mistakes, you develop bad habits. If you make a lot of mistakes, practice becomes a harmful activity because it teaches you more bad English than good English. Some learners make so many mistakes that the more they practice, the worse their English becomes!