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Paragraphs – Science Writing
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Paragraphs are typographic organisers of our text. As such, a paragraph should have a obvious function. Generally, we can state that paragraphs which are well structured across the manuscript is an ingredient for clear writing.

So what makes a clear paragraph?

According to Lunsford and Conners, 2008, a paragraph is “a group of sentences or a single sentence that forms a unit”. In addition a paragraph is a unit of organisation which introduces and treats an idea and every “new idea” forms a new paragraph. But what constitutes a “new idea”? New ideas could be an entirely new idea or it can be a changing perspective on an old idea, or it can be a movement away from an idea.

What are the properties of good paragraphs?

Good paragraphs have the following properties:

  1. A good paragraph is UNIFIED and therefore deals with the same idea.
  2. A good paragraph is COHERENT and therefore contains sentences that work together effectively to develop the idea
  3. A good paragraph is DISTINCT and therefore is self-contained, different from paragraphs that precede and follow it, and communicates its ideas without strong dependence on other paragraphs.


So how do we make unified paragraphs?

When writing in English, we are strongly influenced by the Anglo-American traditions of writing, and the Anglo-American tradition of writing strongly favours the topic sentence. Student in high school and university learn all about the topic sentence and how fundamental it is for their writing. The topic sentence is somewhat build in the structures of good paragraphs. Therefore, to consider how we make unified paragraphs, we have to consider the topic sentence. 

The topic sentence is nearly always the first sentence in the paragraph, which we also call the power position of the paragraph. It can also be the last sentence in some genres. In science writing we’d prefer to have the topic sentence at the beginning and if need be also as the last sentence as a repeated take home message. The topic sentence declares the central idea of the paragraph but does not have to explain it.

For example: 

“We can evaluate the cluster-assisted model by considering three features of our protostar mass and distribution data”

In this example, we can see a clear preview of what the idea of the paragraph is going to be evaluating the cluster-assisted model, and when we keep reading, we will most likely read about this evaluation by considering three features of  our protostar mass and distribution data. As a reader, my expectations are that this is the topic of the paragraph and will most likely read about three features. The topic sentence has given us as readers a clear preview of what is to come.

Other examples: 

bold = topic Italic = Controlling idea 

  1. People can avoid plagiarising by taking certain precautions 
  2. There are several advantages to online education 
  3. Effective leadership requires specific qualities that anyone can develop


How do we make paragraphs coherent?

In order for a paragraph to become coherent, sentences will need to work together to develop the idea which it’s presenting. In other words, logical orders should be created where each other steps made by each sentence relates to the next. For example, when we create logical orders to develop our ideas, these tend to follow the following patterns:

  1. General to specific
    This is a pattern which we commonly see in Introductions where the topic which is presented starts from the general perspective of the research territory (for example) and zooms into a more specific territory the paper investigates.
  2. Specific to general
    The alternative route is often taken when writing the Discussion where the topic zooms back out from the specific results which have been obtained to the more general implications this can have on the field of your research in general.
  3. Least to most important
    Specifically when building up towards a strong argument you wish to make, discussing what is least important, yet relevant enough to support the case, to what is most important, helps to get to the punchline at the end.
  4. Familiar to unfamiliar
    Overall in our writing, readers have an expectations that they are given information which they know before they are given information which they do not know. This roughly means that topics need to have a degree of familiarity. Either in their common knowledge (you decide what that is) or it is something that you have already introduced in the text at an earlier stage and therefore should be familiar to them. Once you have mentioned the familiar you introduce the unfamiliar at which stage the unfamiliar becomes familiar.
  5. Simple to complex
    Like the familiar to unfamiliar rule, readers tend to prefer reading about simple concepts first before being introduced to more complex concepts. For example, you can place rules before the exceptions of these rules and introduce simple cases before more complex cases.
  6. Certain to uncertain
    When presenting the claims of your arguments, these are more often better understood when they are included with certain references and certain material, rather than with references or materials which are uncertain.

When using these simple organisational patterns, you should also include relational devices to make the transition between these patterns coherent. These are often called cohesive devices. Common examples of cohesive devices are: however, first, second, third, then, but, next, also, although, as an example, because, hence, however, in conclusion, next, on the other hand, similarly, specifically, that is, then, until then, etc.

 etc. These are the road sings that provide direction for the readers.

In the following example we can see a clear progression of structure, grammatical tenses, and voice:

We measured enzyme activity in presence of inhibitors with an in vitro assay. We first purified the enzyme in a sucrose gradient. We then added 0.1 umol of purified enzyme to each well of a 96-well plate, and added 0.1 umol of inhibitors to half the wells. We incubatedthe plates at 37 C for 30 min, and then added 0.1 or 1 umol of substrate to each well. Finally, we assayed enzymes activity spectrophotometrically.


How do we make sure our paragraphs are distinct?

To create distinct paragraphs, we have to follow some of the basic rules outlined above. A paragraph should start with a topic sentence. Once the topic has been introduced, the paragraph should provide a complete and self contained treatment of that topic. In other words, the topic should be developed and ultimately lead to a conclusion.

Remember though, that paragraphs, despite having to stand alone, they are not independent from each other.

As we are dealing with science, and science presents complex information, we can use the movement between paragraphs to assimilate this complexity. Paragraphs working together, therefore, move information onto new tracks ultimately leading to the same end point. So, when analysing our paragraphs, we can simply check whether these follow the rules.

  • We can easily spot the redundant paragraphs
  • We can spot the breaks between paragraphs when they are not needed. Or the other way around. We can create breaks in long paragraphs.
  • We can compare paragraphs and find that the topic it expands or are too closely related.