Skip to main content

Common spelling, grammar and syntax errors

Contractions (abbreviated verbs):

Do not use contractions in essays, unless they appear in material you are quoting.
Use ‘does not’, not ‘doesn’t’, use ‘is not’, not ‘isn’t’, use ‘cannot’, not ‘can’t’.

Common Spelling Mistakes

ocurred (NOT occured)
entered (NOT enterred)
propaganda (NOT propoganda)
supersede (NOT supercede)
preferred (NOT prefered)
separate (NOT seperate)


'it’s’ is the contraction of ‘it is’; in contrast, ‘its’ means ‘belonging to it’.
'It’s true that misuse of these terms makes tutors foam at the mouth—an ugly sight. It’s also true that an essay in which this mistake is made is likely to have its final mark lowered by an outraged tutor.'
You can avoid this problem by avoiding contractions: ‘it’s’ should not appear in your essay in the first place, leaving all the more room in its sentences for proper use of the possessive form of ‘it’.

Singulars and Plurals

If the subject of your sentence is singular, you verb must be singular; if the subject is plural, your verb too must be plural. Two nouns whose singular and plural forms are often confused are datum (singular)/data (plural) and criterion (singular)/criteria (plural).
Incorrect: The data is consistent. Correct: The data are consistent.
Incorrect: The criterion are shifting. Correct: The criterion is shifting.

Genitive Apostrophes

To form the possessive of a singular noun, add ’s: the bee’s knees (that is, one bee has many knees).
To form the possessive of a plural noun, usually you will add the apostrophe after the terminal s: the bees’ knees (that is, the many knees of several bees).
The most common exceptions to this rule are the plural forms of men, women and children: men’s, women’s and children's.


Use commas to help the reader negotiate a complex sentence, but do not use them to string together a succession of linked sentences or to link a seemingly endless succession of main clauses. If you use a comma to separate two independent clauses in a sentence, always insert ‘and’ before the second clause: ‘During the suffragette agitation the Liberal party was besieged by angry feminists, and Irish nationalists further destabilised political equilibrium'.
In general, you need a comma where you would naturally pause if reading the passage out loud. If you are using a comma to separate out part of a sentence as a minor digression, remember to put commas both at the beginning and the end of the phrase in question: ‘Decolonisation in the Far East, Japanese occupation policies notwithstanding, was primarily an anti-western impulse’.

Colons and Semi-colons

Use a colon within a sentence as a bridge, either introducing an illustration of a point made at the beginning of the sentence or to introduce a list. 
'Nationalism is often a virulent force: tens of thousands have died in conflicts over nationality in eastern Europe.'
'Vichy collaboration can be ascribed to many forces: self-interest, defeatism and Gestapo entrapment.'
Use a semi-colon to link two thematically related but grammatically independent sentences.
'The erection of the Berlin wall marked a new phase in the divisive Cold War; the subsequent reunification of the two German states arguably signalled a dramatic new development in European unification.'
Semi-Colons may also be used as super-commas, where the complexity of sentence structure renders a comma alone insufficient.
'Imperial developments precipitated large-scale migration: migrants moved from the colonies to Europe; within the different colonies of a single nation, as illustrated by Asian migration to South and East Africa; and also from Europe itself, particularly the Celtic fringe, to colonised territories.'

Passive and Active Voice

Where possible, avoid the passive voice, choosing instead sentence structures in which it is clear who is doing what to whom. Passive voice constructions include phrases such as:
‘the cost of living was raised’, ‘the monarchy was abolished’, and ‘racist ideologies were widely disseminated’.
In all of these passive constructions, it is unclear where agency and causality reside. Attempts to assess and assign agency and causality form the very heart of historical analysis, and use of the passive voice detracts from that essential task. Use active voice constructions wherever possible: they will add clarity to your writing and help you to focus on analysis rather than simple narrative. For example, the passive constructions above might be rewritten as follows:
‘The failure of agricultural production to keep pace with rising birth rates raised the cost of living.’ ‘The monarchy was abolished by a small group of disaffected financiers determined to seize power for themselves.’ ‘Newspaper proprietors eager to increase circulation of their journals were at the forefront of efforts to disseminate racist ideologies at the turn of the century.'