For many students this is their first long term project. Students must choose something which is meaningful to them and will sustain their interest over time. When picking a project, it is important to focus on the topic, not the product/outcome, as this might change, depending on their research.
For example, don't say "I want to make a cookbook, showing international recipes", but say "I want to learn about popular food around the world" - then if your product changes from a cookbook, to a website, app, or cookery lesson, the learning still has the same focus. You might even do research and change your topic to something completely different - you might start off wanting to learn about cooking, but end up researching about the history of food, hunger around the world, or even the environmental impact of the food we eat!