Paragraph Structure

Organized paragraphs ensure clarity in technical writing. As a refresher, paragraphs:

• Are a group of sentences focused on a single topic/subject/idea

• Begin with topic sentences that orient the reader to said topic/subject/idea

• Are both visual and conceptual units 

  • A paragraph is defined not just by its communication of a single idea but also by the proximity of its sentences to one another

An effective paragraph contains four components:

• Topic sentence – establishes the subject of the sentence; in argumentative genres, it makes a claim 

• Supporting sentences - expand upon the topic sentence by providing more detail or evidence

• Concluding sentence – restates the topic sentence, summarizes the paragraph, and establishes the significance of the paragraph within the document as a whole

• Sentence-level transitions – create coherence among the sentences in the paragraph by showing the reader how the writer’s logic progresses

Read the sample paragraph below in its entirety. Can you identify the topic sentence, supporting sentences, and concluding sentence? 

Mechanical engineering students must understand friction because it significantly impacts the performance, efficiency, and longevity of mechanical systems. Friction is the resistance to motion when two surfaces interact, affecting everything from the simplest machines to complex engines. Engineers must accurately predict and manage frictional forces to ensure machinery operates smoothly and efficiently. For instance, excessive friction can lead to wear and tear on a vehicle’s engine, increasing maintenance costs and reducing the lifespan of components. Moreover, unnecessary friction can increase energy consumption and limit the engine’s performance. Conversely, too little friction can cause braking systems to fail due to lack of necessary grip or control. Engineers who understand fiction will be able to design more reliable, efficient, and sustainable mechanical systems.

Here’s the same paragraph with its constituent parts labeled:

Topic sentence: Mechanical engineering students must understand friction because it significantly impacts the performance, efficiency, and longevity of mechanical systems.

Supporting sentences: Friction is the resistance to motion when two surfaces interact, affecting everything from the simplest machines to complex engines. Engineers must accurately predict and manage frictional forces to ensure machinery operates smoothly and efficiently. For instance, excessive friction can lead to wear and tear on a vehicle’s engine, increasing maintenance costs and reducing the lifespan of components. Moreover, unnecessary friction can increase energy consumption and limit the engine’s performance. Conversely, too little friction can cause braking systems to fail due to lack of necessary grip or control.

Concluding sentence: Engineers who understand fiction will be able to design more reliable, efficient, and sustainable mechanical systems.

In addition to a clear topic sentence, supporting sentences, and concluding sentence, this paragraph includes sentence-level transitions. These transitions help the reader understand the relationship between sentences. Writers can create effective transitions by repeating a word or phrase, or by using transitional words or phrases (first, subsequently, as a result, however, therefore, etc.). Read the sample paragraph again. Can you identify the sentence-level transitions?

Mechanical engineering students must understand friction because it significantly impacts the performance, efficiency, and longevity of mechanical systems. Friction is the resistance to motion when two surfaces interact, affecting everything from the simplest machines to complex engines. Engineers must accurately predict and manage frictional forces to ensure machinery operates smoothly and efficiently. For instance, excessive friction can lead to wear and tear on a vehicle’s engine, increasing maintenance costs and reducing the lifespan of components. Moreover, unnecessary friction can increase energy consumption and limit the engine’s performance. Conversely, too little friction can cause braking systems to fail due to lack of necessary grip or control. Engineers who understand fiction will be able to design more reliable, efficient, and sustainable mechanical systems.

Here’s the same paragraph with the sentence-level transitions bolded.

Engineers must understand friction, the resistance to motion when two surfaces interact, because it significantly impacts the performance, efficiency, and longevity of mechanical systems. Engineers must accurately predict and manage frictional forces to ensure machinery operates smoothly and efficiently. For instance, excessive friction can lead to wear and tear on a vehicle’s engine, increasing maintenance costs and reducing the lifespan of components. Unnecessary friction can also increase energy consumption and limit the engine’s performance. Conversely, too little friction can cause braking systems to fail due to lack of necessary grip or control. Engineers who understand fiction will be able to design more reliable, efficient, and sustainable mechanical systems.

Finally, look at the same paragraph written without transitions. 

Engineers must understand friction, the resistance to motion when two surfaces interact, because it significantly impacts the performance, efficiency, and longevity of mechanical systems. They must accurately predict and manage frictional forces to ensure machinery operates smoothly and efficiently. Excessive friction can lead to wear and tear on a vehicle’s engine, increasing maintenance costs and reducing the lifespan of components. Unnecessary friction increases energy consumption and limits the engine’s performance. Too little friction can cause braking systems to fail due to lack of necessary grip or control. Those who understand fiction will be able to design more reliable, efficient, and sustainable mechanical systems.

Although the paragraph is still comprehensible, it lacks cohesion because the transitions are missing.

As you write, be sure that your paragraphs are well structured; this will help your reader understand how your ideas relate to each other to convey your overall message.