Grammar Mistakes To Avoid At All Costs

February 1, 2022

Here in the UK, we are notoriously neglectful with regards to teaching school students English grammar. This really rather atrocious gap in our education leaves many of us lacking a sophisticated understanding of sentence structure and rushing to google how to use the Oxford comma on a regular basis. 

While many of us have come to rely on word processing technology, spelling and grammar checkers will only get you so far. They’ll make sure you don’t fluff the basics but, when it comes to those intricate questions of word order and clauses, it’s every man (/woman) for themselves. So if UK schools’ shoddy approach to grammar has got you agonising over apostrophes, snivelling over semicolons and howling over homophones, we’re here to help.

1. Apostrophes

Apostrophe insecurity can plague even the most confident of writers. So, allow us to do a bit of demystifying.

Once you’ve got your head around ‘it’s’ (meaning ‘it is’ instead of ‘belonging to it’), there’s the matter of plurals to attend to. It’s easy to make the mistake of inserting an apostrophe to pluralise, for example, nouns that include numbers or capital letters, but this is incorrect. So, we don’t write ‘the 1980’s’; it’s ‘the 1980s’. Similarly, ‘two PhD’s’ is not correct, but ‘two PhDs’ is. (Exception: when certain abbreviations or letters are used as nouns, apostrophes are used to pluralise them in order to avoid confusion. For example, ‘he received three B’s in his A-levels’.)

And then we move onto possessives. We know that a singular noun is made into a possessive by using an apostrophe + ‘s’. For example, ‘Henry’s pen’.

But what if the noun is plural, and therefore already ends in an ‘s’? If this is the case, the noun is followed by an apostrophe only, without the extra ‘s’. For example, ‘the cats’ paws’. Don’t be tempted to apply this rule to singular nouns that end in an ‘s’ - these still require our winning apostrophe + ‘s’ combo. For example, ‘Paris’s architecture’. (Here things get pretty sibilant.)

2. Fewer/Less

The central point here is whether we’re talking about countable or uncountable nouns. ‘Fewer’ is used when referring to items that can be counted individually. For example, ‘fewer lemons’. ‘Less’ refers to something (a substance, perhaps, or an abstract noun) that cannot be counted. For example, ‘less water’. 

It’s a nuance most people are aware of, in theory; supermarkets’ frequent use of the incorrect ‘10 items or less’ has become the subject of many a meme in recent years. But the leaning in spoken English is still towards ‘less’, even with uncountables, so incorrect usage can slip out inadvertently in our writing if we’re not concentrating.

3. Affect/Effect

‘Affect’ and ‘effect’ are two of the most commonly confused words in English. They’re what are known as homophones, meaning they’re pronounced the same but spelled differently, so it’s no wonder they trip people up. 

‘Affect’ is generally a verb and means to make something change. For example, ‘incorrect grammar can affect your grades’. ‘Effect’ is usually a noun and means the result of change. For example, ‘the effects of the tsunami were devastating’. Always be sure to double check which one you’ve used.

4. Lay/Lie

Our final vocabulary-based error is popping up more and more. Writers sometimes use ‘lie’ and ‘lay’ interchangeably but it’s important not to fall into this trap because the two, while related, have separate meanings.  

Both are verbs but ‘lay’ is a transitive verb, whereas ‘lie’ is intransitive. Transitive verbs convey doing something to an object, while intransitives do not. So ‘lay’ would be used, for example, in ‘he lays the baby down to sleep’ and ‘lie’ would appear in ‘I’m going to lie down for a bit’. 

The confusion that often arises from these two words is less British than American, but, with the ever growing influx of Americanisms within our culture, we have to keep an eye out.

5. Comma splicing

Beware the misplaced comma! Comma splicing is where two clauses that should be separate sentences are connected using a comma rather than a full stop or conjunction. Commas are wonderful things - the matriarchs of punctuation, capable of bringing order to even the messiest of thoughts. But, alas, they can’t perform miracles, and so simply aren’t able to unite two independent clauses within a single sentence. 

You might have written ‘Shakespeare was a pioneer, he invented numerous English words that are still used today’, but you should have written ‘Shakespeare was a pioneer. He invented numerous English words that are still used today'. You could even take the semicolon for a stroll and use it to replace the full stop. Just make sure you steer clear of commas. 

As tempting as it can be to use a comma to create a long, free-flowing sentence, comma splicing just isn’t appropriate in formal writing. So respect the boundaries of this saintly piece of punctuation and call on it only when it can rise to the occasion.

6. Sentence fragments

As sinful as comma splicing is, it’s important not to go too far in the other direction by using a full stop where there should be a comma. In an effort to create a strong impact, writers sometimes produce stand-alone sentences that in fact can’t reasonably be described as sentences at all. Sentences need a subject and a verb; anything else is a clause, or a sentence fragment, and should be preceded by a comma - not a full stop. 

An example of this: ‘She came into the house. Then sat down’. Part 2 is crying out for a comma or a subject pronoun; the choice is yours. So, either ‘she came into the house, then sat down’ or ‘she came into the house. She sat down’. Sentence fragments occasionally appear in fiction for dramatic effect but they must be avoided in formal writing.

7. The subjunctive 

If you thought the subjunctive mood only existed in Romance languages, here’s a fun fact for you: English has it too. However, it is used much more rarely than in, say, French or Spanish. 

In English we use the subjunctive in expressions that convey suggestion or hypothesis. Basically, it implies that what is being said isn’t based in fact (yet). For example, ‘it is important that she pass her exams’ (instead of ‘she passes’) and ‘if I were you you’ (instead of ‘I was’). 

The subjunctive is becoming less and less common and is often completely discarded in spoken English. But if a reader who knows better catches you dropping it in your written work, your credibility as a writer is bound to go down a couple of notches.

8. Ambiguous modifiers

Modifiers are words that give us further information about part of a sentence. Other languages tend to have more hard and fast rules about where adverbs can go within speech and writing; for instance, French requires them to go directly after the verb with very few exceptions. But in English we tend to scatter them anywhere, which can sometimes lead to confusion.

For example, in the sentence ‘running quickly made me tired’, it’s not entirely clear what ‘quickly’ is referring to. Is it describing the speed at which the person was running or at which the person became tired? In speech this ambiguity is often cleared up by emphasis or tone but it’s trickier in writing. So, always make sure sentences using modifiers are crystal clear by moving the modifiers around if necessary. 

9. Incorrect pronouns

Pronouns, along with verbs, are the basis of language, but it’s easier than we think to use them incorrectly. First let’s have a look at who’s who:

The subjective (or nominative) pronouns, used to refer to someone who is the subject of an action (i.e. doing it) are ‘I’, ‘he/she/it’, ‘we’, ‘they’ and ‘who’. The objective (or accusative) pronouns, used to refer to someone who is the object of an action (i.e. having it done to them) are ‘me’, ‘you’, ‘him/her/it’, ‘us’, ‘them’ and ‘whom’.

Easy enough. But confusion tends to set in when sentences get longer. Maybe it’s because some subjective and objective pronouns overlap, but people often get them mixed up in certain contexts. For example, ‘him and I went to the Park. ’I’ is correct but ‘him’ is off because ‘he’ is doing the action and so a nominative is required instead. So, the correct version would be ‘he and I went to the park’.

10. Passive voice

And last but not least, we have a slightly more nuanced one. The passive voice refers to emphasis being put on the action being done rather than the person or thing doing it. For example, ‘the passive voice is used too frequently by students’.

Using the passive voice is not incorrect (perhaps making its place on this list somewhat questionable). Sometimes, it can be a useful tool for shifting focus onto the action being referred to, or for conveying that the person who carried out the action in question is unknown.

However, overuse of the passive voice can be off-putting for a reader. Inexperienced writers may think it makes their work sound more sophisticated, but often the opposite is true. Firstly, no one trusts an abuser of the passive voice - just look at ‘mistakes were made’; a structure that has been christened ‘the past exonerative’ to reflect how often politicians use it to deflect blame.

Secondly, it simply lacks flair. It’s hard to deny, for instance, that ‘the students’ homework was marked by their teacher’ just sounds a bit off. ‘The teacher marked her students’ homework’ is much more pleasing to the ear/eye. So, if you choose to use the passive voice, make sure you have a good reason for doing so.


Hopefully this list will help you cut down the hours spent wrestling with commas and pronouns in favour of giving your writing’s substance the attention it deserves. Purge your essays of any and all grammatical sins and hand in your coursework safe in the knowledge that no comma is out of place.

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Ella Burgess

Ella is a content writer at Tutor House and explores a range of education centred topics, having previously spent time teaching English while living abroad. A foreign language enthusiast and lover of text art, she is devoted to words in all their forms. She'll happily immerse herself in anything wordy from conceptual art to vintage murder mysteries.

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