You should have a good understanding of grammar rules to score well in IELTS writing.
There is no grammar section in the IELTS test, so why should you learn it? Well, it is true that the IELTS test does not have a section on grammar, but in the writing and speaking sections, you have to express your ideas in grammatically correct English. If you don’t know grammar, you will make a lot of mistakes and your score will suffer. In fact, grammar accounts for about 25% of your total score.
It is impossible to get band 7 or higher if you make a lot of grammar mistakes. The range of your vocabulary is equally important. You should be able to use complex vocabulary that suits the context. Note that you are not supposed to use obscure words with the sole objective of impressing the examiner. If the words do not fit the context, this strategy will backfire. Also pay attention to collocations. These are conventional word combinations. Examples are: heavy smoker, golden opportunity, burning desire and devoted husband. If you say ‘strong smoker’ or ‘big smoker’ you will still be understood, but you won’t sound natural. The IELTS examiner is interested in assessing your ability to use collocations correctly.
Using the correct word form is important too. If you use the noun form of a word instead of the verb form, you will be penalized. This, however, does not mean that you should focus only on grammar. In the speaking section, other elements such as fluency are equally important. In the writing section, task completion and cohesion are two other factors that influence your score.