A thesis statement is the central idea of your essay. Meaning, it is what your essay is mainly about.
OPTION 1: Thesis Statement (what your essay is about)
For example: Did the benefits of Roman expansion outweigh the costs?
The benefits of Roman expansion outweighed the costs.
The benefits of Roman expansion did not outweigh the costs.
OPTION 2: Thesis Statement (what your essay is about with a preview of the three subtopics)
For example: Did the benefits of Roman expansion outweigh the costs?
The benefits of Roman expansion outweighed the costs because __________, ____________, and _________.
The benefits of Roman expansion did not outweigh the costs because __________, ____________, and _________.