(The basic part pf the introduction is the thesis statement. The strength of the thesis statement depends on how well it reveals the topic and its classification. It is to justify the specific categories chosen for this classification).
The thesis statement has a very determined logical structure: theme ® its classification ® chosen categories (the number of categories is suggested to be limited to three in order not to blur the classification).
For instance: Exchange students can face three benefits: education, experience and cultural exchange.
Writers address a number of features and characteristics of two subjects, persons, places and events by contrasting them from one point to another. While the major purpose of contrast is to elucidate ideas and clear their meanings, the readers can easily understand through this device what is going to happen next. Through opposite and contrasting ideas, writers make their arguments stronger which become memorable for readers due to emphasis placed on them. In addition, contrasting ideas shock the audience , heighten drama and produce balanced structures in literary works.
Briefly state your position, state why the problem you are working on is important, and indicate the important questions that need to be answered; this is your "Introduction." Push quickly through this draft--don't worry about spelling, don't search for exactly the right word, don't hassle yourself with grammar, don't worry overmuch about sequence--that's why this is called a "rough draft." Deal with these during your revisions. The point of a rough draft is to get your ideas on paper. Once they are there, you can deal with the superficial (though very important) problems.