Punctuation errors in the use of colons and semi-colons are often the result of confusion about when to use these punctuation marks.

Common student errors include using a semi-colon instead of a colon to introduce lists, failing to use a semi-colon preceding words like however, mistakenly using semi-colons to introduce sentence fragments and misplacing colons when using them to introduce lists.

Colons, NOT semi-colons, are used to introduce lists; for example:

Baddeley's theory divided working memory into three major parts: the central executive, the articulatory or phonological loop and the visual spatial sketch pad.
When under pressure, humans may exhibit the following behaviours: anger, anxiety, sleeplessness, aggression, and poor concentration.
Semicolons, NOT colons, are used before connective words such as 'therefore', 'however', and 'additionally'; for example:

First and second languages are not learned in the same way; therefore, we should not aim to simulate first language learning in the second language classroom.
In March 1810 Macquarie put in a request to the colonial office to set up a bank; however, the bank of New South Wales did not open for business until April 1817.
Colons, NOT semi-colons, can introduce sentence fragments within a sentence.

We are faced with another issue to address: unequal access to information.
There are two options which would alleviate the detrimental effects associated with the split attention effect: reducing the extraneous load on working memory or increasing its processing capacity.
Colons should be placed after the object of the sentence NOT after the verb of the sentence when introducing lists.

When a colon is used to introduce a list it should NOT be placed immediately following a verb because the information following the colon must explain what was presented before the colon.

INCORRECT: These include: physical integration, elimination of redundancy and the use of multimedia instruction.

CORRECT: These include the instructional design principles: physical integration, elimination of redundancy and the use of multimedia instruction.

For more detailed information about using colons and semi-colons in academic writing, click here.