A thesis statement is a summary of the argument you are going to make in your research paper. It should be:

Specific and precise

Too vague to be effective: “Education is important for children.”

More effective: "Outdoor, unstructured play in school is important for the social development of children."

Arguable

Too obvious to make a strong argument: “The 9/11 bombings were a crucial event in U.S. history.”

Stronger argument: "The changes to Homeland Security after the 9/11 bombings had a lasting impact on citizen privacy."

Manageable in scope

Too much content to cover in a four-page paper: "The Civil War was a defining event in American history.”

Manageable for a four-page paper: "The role of women in Civil War medical camps had a significant impact on Women's Civil Rights."

Supported by academic sources

Too much opinion or personal reflection: "Disney's Snow White is the best princess film."

Supportable by sources: "The portrayal of female characters in Disney films changed significantly after WWII."