A thesis statement is your opinion stated as a fact.
Not a Thesis Statement: “To Kill a Mockingbird” won a Pulitzer Prize (This is not an opinion. This is a fact).
Thesis Statement: “To Kill a Mockingbird” won a Pulitzer Prize because it dealt with thematic issues, portrayed the south realistically, and because Scout endeared herself to critics across the globe.
Not a Thesis Statement: The North won the Civil War. (This is a fact).
Thesis Statement: The North won the Civil War because they had access to more resources, had a stronger government, and more soldiers.
This is your opinion. There could be many reasons that the North won the Civil War, but you are able to defend your thesis statement with other sources. Also note that you gave three “reasons” for the North winning. When you give three examples by using the word “because,” you have set up your entire essay, making it easier to write. You know exactly what you are focusing on, so you will not go off on bunny trails throughout the essay. This is how you will set up your essay:
First Paragraph: Introduction, Thesis Statement
Second Paragraph: Discuss the resources to which the North had access.
Third Paragraph: Discuss the strong government the North had.
Forth Paragraph: Discuss the quantity of soldiers.
Fifth Paragraph: Conclusion, restate thesis statement.
For a longer essay you would simply spend more paragraphs on each subject, or add addition reasons that the North won the war.
It is unnecessary in a thesis statement to begin with “in my opinion…”. This essay was written by you! Readers will know it is biased and your opinion. When discussing a book with others we try not to offend them by saying things such as, “I might be wrong but…”, “I kind of think…”, etc. When you are writing an essay there is no reason to be gentle. State your opinions as clearly and concisely as possible and do not waste space by using filler words. A thesis statement should be one sentence only.
If you are having trouble coming up with a thesis statement, please let me know! This is one of the hardest parts of writing an essay and many students in college courses struggle with this as well. I would be happy to help you.