Writing: The Topic Sentence — One Idea, One Paragraph (B1/B2)
🎙 From the classroom: When I submitted my first written assignment on the teacher training course in France, my observer wrote three words: ‘one idea only.’ I had put four ideas in one paragraph. In hospitality, I wrote emails with fifteen points in one paragraph. My teachers always replied slowly. This lesson would have saved me years.
💡 The Idea
A topic sentence is the first sentence of a paragraph. It states exactly ONE main idea. Every other sentence in the paragraph must support, explain, or give evidence for that idea. If a sentence doesn’t connect to the topic sentence, it belongs in a new paragraph.
🗣 Example
❌ Weak paragraph (multiple ideas): ‘Learning a language takes time. I moved to France in 2017. French grammar is very complex and the pronunciation is different from English. Also, food in France is excellent. I visited many restaurants.’
✅ Strong paragraph (one idea): ‘Learning French pronunciation took me two full years. The nasal vowels — sounds that don’t exist in English — required daily repetition to feel natural. Even after passing my C1 exam, I still catch myself over-pronouncing the ‘r’.’
🎯 Try It Now!
Choose the best topic sentence for this paragraph body:
a) ‘La Réunion is a beautiful island in the Indian Ocean.’
b) ‘Getting around La Réunion can be challenging for visitors.’
c) ‘La Réunion has excellent beaches and a dramatic volcanic landscape.’
✅ Check Your Answers
✅ Answer: (b) — it introduces the ONE idea (getting around is challenging) that all three sentences support. (a) is true but the paragraph isn’t about beauty. (c) is about landscape, not transport.
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