Grammar can be loosely described as the set of structural rules that govern the composition of writing. Although it evolves over time, a core set of rules needs to be followed if you are to write clearly and correctly. This guide is not meant to provide a comprehensive list of these rules, but instead focuses on some of the more important ones to learn, as well as considering those that students often find difficult.

For a more comprehensive list, and for more detailed information, you might find it helpful to refer to the following set of resources.

Articles: Using the definite article – ‘The’

You should use the definite article ‘the’ to refer to something when you are referring to something specific (or ‘definite’). In contrast, you should use the indefinite articles ‘a’, or ‘an’, to refer to something non-specific (or ‘indefinite’).

The important thing to bear in mind is that a word on its own cannot necessarily be categorized as requiring the definite or indefinite article; instead, it is the way that you refer to that word that determines which article you should use.

For example, you can write: “I saw the anteater at the zoo,” if you are referring to a specific anteater (perhaps there is only one, or this anteater has been in the news lately and people can be expected to know the specific anteater you are referring to). However, if you saw one anteater of five or six that were in the zoo, you should write: “I saw an anteater at the zoo.”

One quick tip to see whether you require an article in your writing is to read the sentence without it and see if it means the same thing; if it does, then you can safely remove the article.

For example: “Anteaters like the sunshine,” means the same thing when written as: “Anteaters like sunshine,” so you need not use the definite article in this case.

Articles: Using the indefinite articles - ‘A’ and ‘An’

Recall from the previous sub-section that you should use the indefinite articles, ‘a’ or ‘an’, to refer to something non-specific (or ‘indefinite’) in your writing.

You should speak a word rather than read it to help you decide whether to use the indefinite article ‘a’ or ‘an’; although there are some exceptions, you should generally use ‘a’ when referring to a word that makes a consonant sound, and use ‘an’ when referring to a word that makes a vowel sound.

For example, you should write: “A rabbit…” or: “A giraffe…” because these words begin with consonants (and make consonant sounds when spoken). However, you should write: “An elephant…” or: “An anteater…” because these words begin with vowels and make vowel sounds when spoken).

The reason that it is helpful to speak words aloud when deciding whether to use ‘a’ or ‘an’ is because ‘silent letters’ could otherwise confuse you when simply seeing them written.

For example, you should write that: “Professor Reilly scored a hat-trick,” (because the ‘h’ in this word makes a consonant sound), but you should write: “The same player acted in an honourable way when passing up another goal due to an opposition player being injured,” (because the ‘h’ in this word is silent, which means the ‘o’ is the first letter you hear, and this ‘o’ makes a vowel sound).

This same general rule applies when using acronyms in your writing, which is why you should write: “A NASA spacecraft is currently taking pictures of Mars,” but: “An EPA directive ensures that businesses attempt to reduce their carbon emissions.”


Tenses help tell people when something happened (or will happen). For example: “I study biology,” refers to the present (I am currently studying biology), whereas: “I studied biology,” refers to the past (as it implies that I no longer study biology).

There are six basic tenses that we use on a frequent basis, and these are highlighted below, with examples. Note: Consider how the implication of the sentences written for the Present Perfect and Simple Past differ based on the addition of one word (have).

  1. Simple Present: I study biology
  2. Present Perfect: I have studied biology for 12 years
  3. Simple Past: I studied biology for 12 years
  4. Past Perfect: I had studied biology
  5. Simple Future: I will study biology
  6. Future Perfect: I will have studied biology

Although it would be good for you to know the differences between these six basic tenses, and to be able to write simple sentences in each one, the most important thing is to be able to recognise when the tense shifts in your writing; this is not always a bad thing, but it can lead to confusion for your reader(s) and roll in to additional grammar issues. For that reason, you are advised to use the same tense within each sentence (and often within a complete paragraph).

For example, writing: “I have studied biology for 12 years, and I also study chemistry,” is confusing because a reader doesn’t know how long you have studied chemistry for (or whether this is important in the context of what you are writing). In that example, you would have mixed the present perfect tense with the simple present tense. Had you written everything in the present perfect tense (I have studied biology for 12 years, and I have also studied chemistry for seven) this potential confusion disappears.

Subject/Verb Agreement

There are many rules that govern how you should write the verb in a sentence, based on the subject of that sentence (see the set of resources linked to earlier on, at the beginning of this guide, for a more complete list). The three below are the most common rules that you are likely to need to apply in your writing, and these are the rules that can be especially tough to master.

Tip: Remember throughout that the subject comes at the start of a sentence, and it is this – and its relationship with the main verb, that is important, as in:

Richard and I are excited to stop learning about grammar and go for lunch.”

1. Do not be distracted by anything that comes in between the subject and the main verb, as in:

  • Our friend Suzy, along with her fellow physics club members, is [NOT ‘are’] anxious about tomorrow’s test.”
  • My classmate, with all his textbooks, takes up [NOT ‘take up’] a whole library desk.”

2. Collective nouns that imply more than one person/thing are involved are still treated as singular subjects, as in:

  • The team runs [NOT ‘run’] during training.”
  • The Physics Club watches [NOT ‘watch’] videos at their meetings.”

3. When your writing includes a compound subject that is joined by ‘or’ or ‘nor’, the verb should agree with the part of that subject that is closest to the verb, as in:

  • Neither Suzy nor her friends, Claire and Ash, want [NOT ‘wants’] to take the new class.”
  • Alana or Jonny is [NOT ‘are’] is going to write up the lab report.”

Parallel Structure

Much like consistency in verb tense, consistency in the form of linked parts in a piece of writing is important for clarity and readability. By this, we mean that the verb endings and related phrases and clauses within a sentence should all follow the same pattern.

For example: “Scientific understanding is improved by researchers exploring new possibilities and communicating their findings,” is written in parallel form and sounds smooth when you hear it.

On the other hand: “Scientific understanding is improved by researchers exploring new possibilities and when their findings are communicated,” is not written in parallel form, and is consequently harder to interpret. This should be corrected by changing the red portion to “…communicating their findings.”

The rule of using the same parallel structure in your writing should be applied whether you are writing complete sentences, or listing things.

For example, in this guide we are hoping to help you: use the definite and indefinite articles appropriately, write your tenses consistently, check that your subjects and verbs align correctly, and ensure that the parallel structure of your writing reads smoothly.

Grammar Quick Quiz

  • Do the following sentences show the correct use of the indefinite and definite articles? Note: If incorrect, think about how you would re-write them correctly.
  • Do the following sentences mix tenses? Note: If they do, think about how you could re-write them to make sure they were in the same tense.
  • Which form of the verbs should be used to fill in the gaps in the following sentences?
  • Q9: Which of the sentences in the paragraph below is NOT written in parallel form? Note: Think about how you could re-write it to make sure it is.

    Sentence 1: When lecturing, my professor mimics a TV reporter by presenting information in a newsworthy way, removing any boring parts, and never forgets to explain important jargon. Sentence 2: At the end of her most recent class, we closed our books, were turning off our computers, and pushed our chairs under the desks when the next class barged in.
  • Q10: Which of the sentences in the paragraph below is NOT written in parallel form? Note: Think about how you could re-write it to make sure it is.

    Sentence 3: The first student to enter was listening to his iPod, the second was chatting, and the third shouted a coffee order to his friend. Sentence 4: He soon realized everyone had heard him, so I bet he wished he could have turned back time, switched off his iPod, and walked into the classroom as normal.