Writing paragraphs

What is a paragraph?
A paragraph is a group of connected sentences which develops one new topic, idea or theme. They are the “building blocks” of your writing, dividing it into easy-to-follow, comprehensible parts.
Essays are usually made up entirely of paragraphs; reports or other types of more technical writing will be written in sections, but within the sections there will be paragraphs as well as bullet points, lists, figures etc.

How long should a paragraph be?
As noted above, a paragraph needs to develop an idea or new aspect of an argument, and it is impossible to do this in just a sentence or two. It is usually recommended, therefore, that in typical student writing a paragraph should be a minimum of five or six sentences. It shouldn’t normally be shorter than this, but may be longer, depending on the overall length of the writing (the longer the writing, the longer the paragraphs can be: books may contain some very long paragraphs).
The most common mistake made in student writing is to make paragraphs too short. If you just write a sentence or two, two or three lines, and then start what looks like a new paragraph, it leaves a bad impression. Your writing may tend to look, and read, more like a series of notes or a list of simple points, possibly indicating that you have not thought through the ideas and have not developed them sufficiently. Alternatively, it may just mean putting some of these fragments together to make one paragraph, as long as they are linked. Don’t put unrelated ideas or information together in a paragraph. A typical 1.5 or double spaced page would normally contain just 2-3 paragraphs.

Don’t go to the opposite extreme and make your paragraphs too long. Over-long paragraphs make your writing difficult to follow and indicate that you are probably not in control of your ideas. And remember that one paragraph = one point, so if your essay just contains three or four paragraphs, this may mean just three or four ideas.

What is the structure of a paragraph?
It would be wrong to say that all paragraphs must follow a set structure; this would make your writing very mechanical, boring to read and would hinder your flexibility in answering the specific question. Instead, paragraphs need to contain some, or all, of the following components in order to sufficiently develop the point:
some sort of “topic sentence” or introduction stating what the paragraph is about. This would normally, but not always, come at the beginning of the paragraph.
explanation or definition of any terms which may be unclear.
evidence for any assertions you make: references to the sources you have used; examples, data, statistics, illustrations etc.
evaluation of this evidence or data; comparison or contrast with other information; analysis of causes and reasons; examination of effects and consequences; discussion of issues raised.
awareness of the implications of any of the above.
drawing of conclusions if appropriate
Your paragraphs should always be coherent, with the sentences linked together (see Guide 1.39). The end of the paragraph may link back to the introduction to show how the argument has developed, and may also link forward to the following paragraph. And particularly in shorter pieces, you may want to make regular reference to the specific question you are answering.

How to separate paragraphs
You must make it clear when one paragraph ends and a new one begins. Traditionally, you would “indent” the first line of the new paragraph, start it a few spaces in. Nowadays, most people leave a line space between paragraphs, without indenting the first line: this is probably the easiest thing to do. Remember that if you are double spacing your writing already, you’ll need to put in an extra space. Don’t mix the two possibilities.

Sample paragraphs
A
Irrigation schemes are a vital source of food production in most developing countries. Currently it is estimated that between 35% of world food is produced by irrigation (Bos 1992) and in parts of South East Asia where rice is the staple crop, up to 60% of food is irrigated (Yudelman 1994). While it is acknowledged that the role of small scale irrigation in development and rural food security is important, the medium and large scale sector should not be ignored for important reasons of urban and national food security (Elahi 1992). FAO have estimated that the annual global growth rate for gross agricultural production should be 3.8% most of which will have to come from new or rehabilitated irrigation schemes (Bos 1992).

(If a little bland, this has an introductory sentence that gives the theme of the paragraph followed by sentences that keep to the theme but enlarge on it, whilst debating the pro's and con's of small and large scale irrigation).

Source: http://www.uea.ac.uk/menu/acad_depts/dev/keyskills/cognitive/paragraphs.htm

B
From P. Harvey, Health Psychology, Longman, London 1988
(1) While many cancers are both treatable and curable, the nature of the treatment process may have important pyschosocial dimensions. (2) Many treatments are distressing and uncomfortable (e.g. radiotherapy and chemotherapy) or painful (e.g. surgery) or may be disfiguring (e.g. mastectomy, when the breast is removed).(3) Such procedures are carried out on patients and not simply on bodies. (4) The reactions to such treatments may influence both their efficacy and the cooperation of the patient. (5) Furthermore, the care staff will have to deal with patients who are anxious or distressed and to participate in treatments which they themselves find distressing, despite the clinical benefits which may accrue to the patient.
[The topic sentence is sentence (1). The other sentences develop the topic by giving examples (2) and by setting out some of the implications of the topic (3) (4) (5).]

C
From S.Hall et.al. The Study of Culture (Unit 6) Open University Press, Milton Keynes 1977.

(1) Ideology is yet another of those concepts developed and discussed within the social sciences which defy simple definitions. (2) Rather than being a simple conceptual tool in the hands of the sociologist or the political scientist, ideology rather provides a focal point for a series of intellectual tensions and arguments. (3) In public discussions, for example, the term 'ideology' is used in a fairly loose and unsystematic way. (4) When Keith Joseph calls another politician's speeches 'ideological', the implication would be that the politician was wrong, that he presented an inaccurate view of reality. (5) This pejorative use of the term 'ideology' to mean a distorted view of reality is used by people at both ends of the political spectrum to discredit the opposing view.
[This one is a bit more complicated. You could say that sentence (1) is the topic sentence, or that sentence (2) is. Both these sentences say roughly the same thing. Then sentences (3) and (4) give examples, and sentence (5) sums up. The whole paragraph develops the topic by setting out some of the complications in it.]

D
From P. Ashworth, 'Interpersonal Skill Issues Arising from Intensive Care Nursing Contexts', in C. Kagan (ed) Interpersonal Skills in Nursing, Croom Helm, Beckenham 1985.
(1) It is evident that full and effective use of all communication channels requires the physical, emotional and intellectual capacity to send signals which convey their intended meaning and to receive them, and also some common understanding with those with whom it is sought to communicate. (2) But this is precisely what most patients in intensive care units often do not have. (3) All are restricted in their ability to express themselves by body movement and personal appearance. (4) They are usually unfamiliar with being in a situation where they are physically dependent on other people; where bodily functions usually performed independently in private require assistance and/or permission, and are matters for relatively public discussion; and where they may not understand the physical objects, activities and sounds (including much of the verbal interchange) around them. (5) They need information about their own condition, and the environment and expectations; yet in order to conform to the traditional expectations of the 'good patient' (seen as passive and undemanding), and because they do not feel confident of knowing the right words to use, they are often unwilling or unable to pressure staff to provide it. (6) The patients' self-esteem may be diminished by illness and dependency, thus making them unwilling or unable to persist in their efforts to gain the information they need.

[This is another example of a first sentence which isn't the topic sentence. Most of this paragraph develops a topic of the difficulties faced by patients in intensive care: sentences (3), (4), (5) and (6) all do this. So these sentences are actually developing the topic which is stated in sentence (2), not sentence (1). What then is the function of sentence (1)? It isn't the topic sentence. Instead, it is the link back to what has gone before. The paragraph immediately before this one discusses different kinds of communication, both verbal and non-verbal, and shows how important they are. So sentence (1) links to that, before starting the particular topic of the difficulties which affect patients in intensive care. This is a very common structure for paragraphs - a first sentence which sums up a situation, followed by a sentence which starts a more specific topic within that situation.]