Write a perfect topic sentence with examples and exercises

Hello everyone, after publishing lessons about grammar in my previous articles, today's one is in the field of writing.

Writing a good topic sentence,I'm going to share with you what I've Learned from my professor of writing. Firstly,  a topic sentence is the key to start writing a paragraph that discuses something or what ever your reason of writing it. Now, you will be good and learn how to start your journey in writing.

Topic Sentences 

Firstly wondering about some questions :
What is a topic sentence ?
What does it do?
How I can write one?

The topic sentence is the first sentence in a paragraph,it introduces the main idea of the whole paragraph,and to write your own you should summarize the main idea of your paragraph,for the purpose of reminding the reader of what's the paragraph is about. 

A good topic sentence should include either of the following :

- One clear topic

Weak : It's important to have friends,and also to do well in school.

Strong : I don't think I will ever have a better friend than Heather.

- An opinion or idea about the topic
Weak : I have been studying karate.
Strong : studying karate has given me strength and self-confjdence.

- A good topic sentence should NOT be :
- Too broad (too much to write about)
Weak : Australia is an interesting country.
Strong : on my visit to Australia, I saw many unusual animals.

- Too marrow ( not enough to write about )
Weak : school starts at 8:30 a.m
Strong : getting ready for school in the morning is more difficult than any of my classes.

Topic sentence exercises :
Choose the best topic sentence for each group of supporting sentences. Write it on the line provided.

1.)_________________________________________________. North Americans send cards for many occasions. They send cards to family and friends on birthdays and holidays. They also send thank-you cards, get well cards, graduation cards, and congratulation cards. It is very common to buy cards in stores and send them through the mail, but turning on the computer and sending cards over the Internet is also popular.

a) Sending cards is very popular in North America.
b) Birthday cards are the most popular kind of card.
c) It is important to send thank-you cards.

2.) ________________________________________ .First of all, we need money to repair old roads and build new roads. We also need more to pay teachers’ salaries and to pay for services such as trash collection. Finally, more tax money is needed to give financial help to the poor citizens of the city. It is clear that the city will have serious problems if taxes are not raised soon.

a) We should raise city taxes.
b) City taxes are too high.
c) City taxes pay for new roads.

3.)_________________________________________ . For example, a person can have breakfast in New York, board an airplane, and have dinner in Paris. A businesswoman in London can instantly place an order with a factory in Hong Kong by sending a fax. Furthermore, a schoolboy in Tokyo can turn on a TV and watch a baseball game being played in Los Angeles.

a) Airplanes have changed our lives.
b) Advances in technology have made the world seem smaller.
c) The fax machine was an important invention.
Add your answer on comment. (Good luck)
Finaly,I hope you've enjoyed this lesson of how to form a topic sentence in English :)