(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.