Before you start browsing for ideas, check the assignment requirements carefully to make sure your topic satisfies your instructor's requirements.
All these will affect your choice of topic. For example, if your instructor wants you to write a 10-page argumentative paper, choose a topic that is controversial or has aroused debates. Make sure that there is enough information for you to spread it out into 10 pages.
You can find topic ideas from different sources, such as:
Looking through the table of contents of your textbook or a book related to your course can give you some ideas for a paper.