Teach students to ask questions of the topic to narrow it down. Think of questions in terms of "when," "where" and "why." For example, one strategy you can explore in the lesson plan is narrowing the topic by time, or asking "when?" Give students a broad topic, such as European History. Then ask them what time period they would like to focus on, such as the Renaissance, mid-20th century or 19th century European history. Within that time frame, ask them to think of "where?" For example, a student can choose Germany in the 19th century, France during the second World War, or Italy during the Renaissance. Continue to ask questions of the topic until students come up with a topic narrow enough for a paper.
Another lesson plan makes use of visual aids to help students narrow research topics. Instruct each student to draw an upside-down triangle on a sheet of paper, or draw one on the board. At the top of the triangle, where it is widest, write a very general topic, such as "cooking." Ask the students to come up with a slightly more narrow topic that deals with cooking, such as a type of cultural cuisine. Write that below "cooking." Below the cuisine, write a word or phrase that deals with a specific aspect of it, such as French stews or Japanese sushi making. Finally, below the third topic, have students write a very specific and narrow topic, such as "History of Beef Bourguignon."
Use an active learning lesson plan to help students narrow topics. Divide the class into groups of three to five students. Give each student a large topic and a set of flashcards that contain words that relate to the topic. If the large topic is European history, the words on the flash cards could be "World War II," "unification," "French revolution," "peasants," "bourgeoisie," "Germany" and so on. Each group should arrange the words on a flat surface and connect the words that seem to go to together. For example "French revolution" pairs well with "bourgeoisie," and "unification" goes with "Germany." After a few minutes, ask the students in each group to share topics that they discovered.
Once students are familiar with asking questions or using visual aids to narrow down topics, introduce them to the SOCRAPR method to further refine and reduce a topic. SOCRAPR stands for "Similarities, Opposites, Contrasts, Relationships, Anthropomorphisms, Personsification, Repetitions." Using "similarities" or "opposites" to narrow a topic on the French Revolution, a student can compare it to the American Revolution. Using "relationships," the student can examine the relationship of the poor to the bourgeois or to the king and queen.