When developing supervisor interview questions, review the job description and the person specification, which is the description of the person required for the job. Use these documents as a reference to identify essential and desirable skills required to fulfil the role. Tailor questions around the essential skills.
Consider when you are going to write the questions. Writing the questions prior to selecting candidates for interviews ensures you fit questions around the job rather than the people you are going to interview.
Each essential skill should have a key open-ended question that shows how a candidate behaved in the past. Past behavior is one indicator of future behavior, and if leading a team is an essential skill for the job, ask a question that allows candidates to demonstrate they have leadership skills. One example of such a question is: "Please tell me about a time you motivated a team to complete a task." Follow up with questions for clarification and for probing details.
Another consideration is to have a complete paper trail to protect against complaints in the recruitment process. For example, you can use the same interview questions for all identical supervisory job vacancies to safeguard against the possibility of discrimination or favoritism.