At the earliest stage of the thesis process, students are exploring ideas, developing a topic. Some will have good ideas that are simply too broad to be studyable, like, "I want to study crime." Some will have focused ideas that would be great for a Master’s thesis or a Doctoral dissertation, but not doable as an undergraduate thesis or project. Some students will have an area of interest but no topic and no idea how to approach the area. And some students will have no real idea at all. (Maybe they took a course from an instructor and found it interesting, so they decided to approach that instructor.)
At this stage, it’s tempting for a potential mentor to say, "Sure, I’m willing to work with you. Think about what you want to study and come back when you have some ideas." Faculty should resist this temptation, because students need a lot of help during this formative stage. They need help to transform a vague interest into a doable project. They need help to fashion testable hypotheses or working questions. They need help to translate their hypotheses or questions into a realistic research plan or project schedule. They need help -advice, guidance - with their review of the literature and their actual project and their drafts. Why? Because they’ve never done anything like this before. Work closely with them and help them turn their ideas into an excellent undergraduate thesis.