Originally Posted by Umer

Each and every sentence of introduction is worthy.
Introductory paragraph itself is a gist of what to expect from the essay written below.
There is a high probability that most examiners will decide in their minds the destiny of the essay after they read introduction.
Writing a gist of the gist is something that will take at least a year of practice itself.
So rather than concentrating on writing a thesis statement for the introduction, concentrate more on writing an impressive introductory paragraph.

Thesis statement for other paragraphs can be done rather easily and it is a good practice if you can do that. But this practice alone cannot give you good marks. There must be proper English language usage, proper sentence structure, proper usage of vocabulary, an impressive style of writing that captures the examiner, depiction of the relevant knowledge regarding the topic, logical arrangement and argumentation. All these factors count to make an excellent essay.