What information do you need to answer your main question?
The main research question cannot be answered in a few words. That is why you split a main question into sub-questions. Each sub-question contributes to answering your main question. If you have answered all sub-questions in your research, it should provide the answer to your main question as well.
Tips for formulating sub-questions:
Sub-questions meet the same requirements as the main question
Sub-questions are derived from the main question; what do you need to know to answer the main question?
Sub-questions are less complex and more specific than the main question
Sub-questions are a tool to help you divide your complex main question into smaller sub-subjects. They create an overview for you as a researcher, but also for the reader who is about to read your research report.
How many sub-questions you need depends on how complex your research is. Assume 2 to 7 sub-questions
Place sub-questions in a logical order, this helps to structure and formulate your research.
A sub-question is not a question leading to a definition.