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Writing lesson · Informational writing
Write a Strong Paragraph: Topic Sentence, Details and Closing
Write an informational paragraph with a clear topic sentence, details that stay on topic and a closing sentence. Sort details and fix one that wanders.
The idea
Stories use hooks and feelings to pull readers in. Informational writing has a different job: it explains or teaches something. One of its main building blocks is the paragraph, a group of sentences about one main idea.
A strong paragraph has three parts. The topic sentence usually comes first and tells the reader the main idea: "Tobogganing is a great way to enjoy a snowy day." The supporting details come next. They are reasons, facts or examples that back up the topic sentence. The closing sentence comes last and sums up the main idea in new words.
Every detail has to earn its place. Ask one question about each sentence: does this help explain my topic sentence? In a paragraph about tobogganing, a sentence about warming up with hot chocolate afterward might fit. A sentence about your cousin's new phone wanders off topic, even if it is true and interesting. Take it out or save it for a different paragraph.
Linking words help the reader follow along: first, also, another reason, for example. A closing sentence often starts with "That is why" or "For all these reasons". Try not to copy the topic sentence word for word. Say the same idea in a fresh way, or tell the reader what to do next.
See the difference
A first attempt
I like skating. Skating rinks have ice. My cousin lives in Ottawa. Last summer I got a new bike. You should try it.
An outdoor rink is a great place to spend a winter afternoon. First, skating keeps you moving, so you warm up quickly even on a cold day. Also, you do not need a team or a uniform, just skates and a helmet. Another reason is that you can bring friends and play tag or a game of shinny. For all these reasons, grab your skates the next time the rink opens and give it a try.
Why this works: The clearer version starts with a topic sentence that names one main idea. Every sentence after it gives a reason that supports that idea, and linking words (first, also, another reason) connect them. The first attempt jumps to Ottawa and a bike, which wander off topic, and "You should try it" does not say what "it" is. The new closing sentence sums up the idea in fresh words and tells the reader what to do.
Worked examples
Example 1 · Write a topic sentence
You want to explain why fall is a good season for a family walk. Write a topic sentence.
- Name the topic: fall walks.
- Say the one main idea you will explain: they are worth doing.
- Keep it to one sentence. Save your reasons for the details.
Fall is one of the best seasons for a family walk.
Example 2 · Sort the details
Topic sentence: "Board games are a good way to spend a rainy day." Which details support it? (a) The whole family can play together. (b) Many games let you practise counting or planning. (c) My grandma lives in Calgary. (d) You can play without going outside.
- Read each detail and ask: does it explain why board games are good on a rainy day?
- (a), (b) and (d) each give a reason, so they support the topic sentence.
- (c) is about where Grandma lives, so it wanders off topic.
Keep (a), (b) and (d). Remove (c).
Example 3 · Fix a wandering detail
Find the sentence that wanders off topic: "Libraries are great places to visit after school. You can borrow books for free. Many libraries have clubs and quiet places to do homework. My favourite food is pizza. You can also borrow movies and audiobooks."
- The topic sentence says libraries are great places to visit after school.
- Check every other sentence against it.
- Pizza has nothing to do with libraries, so that sentence does not belong.
Remove "My favourite food is pizza."
Example 4 · Write a closing sentence
Topic sentence: "Soccer is a fun sport for kids to try." Write a closing sentence that does not copy it.
- Remember the main idea: soccer is fun to try.
- Begin with a closing phrase such as "That is why" or "For all these reasons".
- Say the idea in new words, or invite the reader to try it.
That is why you should grab a ball and join a game at the park.
Common mistakes
Why this fails: The reader has to guess what the paragraph is about. Tell them the main idea in the first sentence.
Why this fails: A fact about your cousin's dog may be true, but in a paragraph about why winter is fun, it wanders off topic.
Why this fails: Repeating the exact words sounds like a mistake and adds nothing. Sum up the same idea in fresh words.
Why this fails: "Summer is fun and my school is big" leaves the reader wondering which idea the paragraph is about. Choose one.
Foundation
Foundation practice
Find the parts of a paragraph and spot details that do not fit.
1. These sentences belong in one paragraph. Which one should be the topic sentence?
- You can splash in the waves.
- You can build sandcastles with a bucket.
- A day at the beach is full of fun things to do.
- At lunch, you can have a picnic on the sand.
2. Topic sentence: "Apple picking is a fun fall activity." Detail: "You get to choose the apples you want right from the tree."
- Supports the topic sentence
- Wanders off topic
3. Topic sentence: "Apple picking is a fun fall activity." Detail: "My brother is learning to play the trumpet."
- Supports the topic sentence
- Wanders off topic
4. "For all these reasons, a library card is one of the best things you can own." Which part of a paragraph is this?
- Topic sentence
- Supporting detail
- A hook for a story
- Closing sentence
5. In a paragraph about why dogs make good pets, which part is "For example, a dog will happily go on walks with you every day"?
- Supporting detail
- Topic sentence
- Closing sentence
- A detail that wanders off topic
Practice
Practice practice
Choose the best topic and closing sentences, and fix a paragraph.
6. Topic sentence: "Swimming is a useful skill to learn." Which detail does NOT belong?
- Swimming can help keep you safe near lakes and pools.
- My swimming coach drives a red car.
- Swimming is good exercise for your whole body.
- Once you can swim, you can try sports such as water polo.
7. Details: Pumpkins can be carved into jack-o'-lanterns. Pumpkin seeds can be roasted for a snack. Pumpkin can be baked into pie and muffins. Which topic sentence fits these details best?
- Pumpkins are orange.
- Halloween is on October 31.
- Pumpkins can be used in many different ways.
- I like pumpkin pie.
8. Topic sentence: "Riding a bike to school has many benefits." Which closing sentence is best?
- Riding a bike to school has many benefits.
- My bike is blue and has a bell.
- First, you get exercise on the way.
- That is why biking to school is a smart and healthy choice.
9. Which linking word fits best? "Snowshoeing is easy to learn. ___, it lets you explore trails in deep snow."
- Also
- But
- Because
- Once upon a time
10. This topic sentence has two big ideas: "Hockey is exciting and my school has a big gym." Rewrite it so it has one main idea.
11. Remove the sentence that wanders off topic, then add a closing sentence: "Gardening is a great hobby for kids. You get to watch seeds grow into plants. You can grow vegetables to eat. My sister's birthday is in May."
Think
Think practice
Explain your choices and plan a paragraph of your own.
12. In a paragraph about why hockey is fun, a writer adds: "The arena in my town was built a long time ago." It mentions hockey's arena. Why does it still wander off topic?
13. Which supporting detail gives the strongest reason for "Camping is a great way to spend a weekend"?
- Camping is fun.
- At night, you can see far more stars than in the city.
- Tents come in many colours.
- I have been camping before.
14. Put these sentences in order to make a paragraph: (a) That is why the school book fair is worth a visit. (b) The school book fair is a great place to find your next favourite book. (c) Also, you might discover a new series or author. (d) First, there are lots of books to look through in one room.
15. Plan a paragraph about why your favourite season is worth enjoying. Write a topic sentence and list three supporting details as short notes.
Your turn to write
Choose a place, game or season you think is worth trying: a park, a board game, a sport, a festival or a time of year. Write one paragraph of five to seven sentences that explains why. Start with a topic sentence, give at least three supporting details, and end with a closing sentence.
Helpful sentence starters
- ___ is a great ___ to try because ...
- First, ...
- Another reason is that ...
- For example, ...
- That is why ...
- For all these reasons, ...
Write in a notebook or a document. The model and checklist are available without signing in.
Check and improve
- My first sentence is a topic sentence that names one main idea.
- I gave at least three supporting details: reasons, facts or examples.
- Every detail helps explain my topic sentence. I removed any that wander off topic.
- I used linking words such as first, also, another reason or for example.
- My closing sentence sums up the main idea in new words instead of copying the topic sentence.
This checklist is for parent-and-child self-review. No automatic writing score is assigned.
Answer key
- 1. A day at the beach is full of fun things to do.
It states the main idea. The other three are examples of fun things to do at the beach, so they are supporting details. - 2. Supports the topic sentence
It gives a reason apple picking is fun, so it backs up the main idea. - 3. Wanders off topic
The trumpet has nothing to do with apple picking. It may be true, but it belongs in a different paragraph. - 4. Closing sentence
"For all these reasons" points back to details already given, so this sums up the paragraph at the end. A topic sentence introduces the idea, and a supporting detail gives only one reason. - 5. Supporting detail
It gives one example of why dogs make good pets. It is too specific to be the main idea, and it does not sum anything up. - 6. My swimming coach drives a red car.
It mentions swimming, but it does not explain why swimming is useful to learn. A detail can use the same word as the topic and still wander off topic. - 7. Pumpkins can be used in many different ways.
All three details are ways to use a pumpkin. Colour, the date of Halloween and liking pie are true, but none of them covers all three details. - 8. That is why biking to school is a smart and healthy choice.
It sums up the idea in new words. The first copies the topic sentence, the second wanders off topic, and the third is a supporting detail, not an ending. - 9. Also
Also adds another reason. But signals a contrast, Because would need a reason to follow it, and Once upon a time starts a story, not an informational paragraph. - 10. Example: Hockey is an exciting sport to watch and play.
Keep one idea that the whole paragraph can explain. The gym could be the topic of a different paragraph. - 11. Remove "My sister's birthday is in May." Example closing: That is why every kid should try planting a small garden.
The birthday does not explain why gardening is a good hobby. The closing sentence sums up the main idea in new words. - 12. It does not give a reason hockey is fun. It is a fact about a building, so it belongs in a different paragraph.
Test every detail against the main idea, not just against the topic word. - 13. At night, you can see far more stars than in the city.
It gives a specific reason the reader can picture. "Camping is fun" only repeats the topic sentence, tent colours do not explain why camping is great, and "I have been camping before" tells about the writer, not a reason. - 14. b, d, c, a
The topic sentence (b) comes first, the details with First (d) and Also (c) come next, and the closing sentence starting with That is why (a) comes last. - 15. Example: Topic sentence: Winter is the most exciting season of the year. Details: tobogganing on big hills; building snow forts; warm drinks after playing outside.
Check that each note is a reason for your topic sentence. Turn the notes into full sentences when you write.