A college student got a C on a paper that claimed it was still possible to ratify the 27th amendment. It was ratified ten years later.

Gregory Watson was a student at the University of Texas when he came across research about an un-ratified amendment to the constitution. Intrigued he wrote a paper with the thesis that the amendment was still possible to ratify. 

His teacher, Sharon Waite, gave Watson a C on the paper. She claimed that his thesis was unlikely, irrelevant to modern politics or government. Ironically, it would take only ten years for that exact amendment to be ratified as the 27th amendment. 

The 27th amendment says that laws about salaries for congress can’t take effect until the next session of Congress. Watson himself was instrumental in seeing that it got ratified. 

He wrote letters to individual states in order to convince them to ratify the old amendment, which could be ratified since it had no deadline for ratification. Maine was the first to ratify it, and was followed by Colorado. It took ten years, but all of the state legislatures ratified it and it was adopted as an amendment. 

Watson also did more research into ratification and history. He found out that Mississippi had never ratified the 13th amendment, the amendment barring slavery. With some letters to African-American state legislators, the amendment was symbolically ratified by Mississippi in 1995. 

(Source)