A paragraph is the basic organisational unit of written discourse. In academic and formal writing, a well-constructed paragraph develops a single main idea through a predictable internal structure: topic sentence, supporting sentences, and (optionally) a concluding sentence.
The Topic Sentence states the paragraph's main idea and controls its scope. It typically appears first, orienting the reader to what follows. Everything in the paragraph should connect to and develop this controlling idea.
Supporting sentences develop the topic sentence through:
Optional in body paragraphs but common in academic writing. It may summarise the paragraph's point, link back to the topic sentence, or transition to the next paragraph.
Unity: A paragraph has one main idea. Every sentence must relate to and develop the topic sentence. If a sentence introduces a new main idea, it belongs in a new paragraph. Lack of unity is one of the most common weaknesses in L2 academic writing.
Coherence: Ideas flow logically from one sentence to the next. Coherence is achieved through:
| Problem | Description | Teaching response |
|---|---|---|
| No topic sentence | Paragraph drifts without a clear controlling idea | Practise writing topic sentences from prompts |
| Off-topic sentences | Supporting details unrelated to the topic sentence | Highlight-and-delete exercises |
| Underdeveloped | Topic sentence + one or two thin sentences | Model how to expand with PEEL (Point, Evidence, Explanation, Link) |
| List-like structure | Series of disconnected points | Teach Cohesion devices and logical connectors |
| Over-long paragraphs | Multiple ideas crammed into one block | Teach paragraph division based on shifts in main idea |
There is no universal rule for paragraph length. In academic writing, 5-8 sentences is a common guideline, but the real criterion is whether the idea is fully developed. A three-sentence paragraph that makes its point effectively is better than an eight-sentence paragraph that rambles. In IELTS Writing, body paragraphs of 4-6 sentences typically provide sufficient development.