It is very important to be able to develop a topic sentence in the IELTS Writing Exam. If you cant support your main idea with explanation or examples, you simply arent fulfilling the requirements for coherence and cohesion. This is a difficult skill to master, but there are ways to practice it.
Practice
Look at the following topic sentences. Try to write two supporting sentences for each one.
In many countries, schools are facing increasing problems with pupils behavior.
Obesity is a major health problem in many countries and children are just as much at risk as adults are.
Remember that your sentences must follow logically. That means they must flow naturally from one point to the next in other words, developing an idea. Also, you should avoid repeating words or phrases where possible.
Sample Answers
Here are my two answers for the above topic sentences.
In many countries, schools are facing increasing problems with pupils behavior. One such example is truancy, which is a significant problem in the United Kingdom. It has gotten so bad lately that authorities have begun fining parents to solve the problem.
Obesity is a major health problem in many countries and children are just as much at risk as adults are. Part of the problem is that fast food restaurants are advertising directly to children.Children dont have the ability to resist these advertisements and are easily captivated by cheap marketing ploys.
In the first example, I developed the topic sentence by mentioning one kind of behavioral problem truency [which means being absent from school]. I further developed this by explaining how severe the problem has become.
In the second example, I developed the topic sentence by elaborating upon the general problem of childhood obesity, showing why children are getting so fat. Each sentence builds logically upon the previous one.