Research questions guide your research and analysis. These questions go beyond what can be answered by yes or no and surpass factual questions that can be easily answered with a statement of fact. Research questions should focus on how and why things happened. These questions will help you focus your research and develop your argument as you progress throughout your project.
From A Pocket Guide to Writing in History by Mary Lynn Rampolla:
This website also gives some really helpful ideas for writing research questions.
This is a great video on developing strong research questions.
Here is an example of a thesis statement:
The return of Egyptian government to a military dictatorship only three years after the popular uprising of 2011 was inevitable given that Mubarak's deep-rooted regime largely remained in power, the opposition parties had had little opportunity for governance and had no cohesive vision, and the democratically elected Muslim Brotherhood government proved to be weak and incompetent.