CIRCLES stands for:
Comprehend the situation (What? Who? Why? How?)
Identify customer (personas)
Report customer needs (As __, I want __ so that __.)
Cut through prioritization (ROI estimate)
Evaluate trade-offs (thoughtful, analytical, objective)
Summarize recommendations (Recap)
CIRCLES is not a hard-and-fast rule but a useful heuristic for approaching project design and product management case questions. One of the most important steps is clarifying and asking questions. This process can help you brainstorm needs and features. Identifying needs can help you understand the problem better.
Once implemented, your feature should help solve a problem. You want to evaluate a few different choices and select the ones that are the most cost efficient and important. Be sure to summarize your decision, as well as provide possible negative effects of your decision and reasoning behind why you made the choice. Before you start listing possible routes, make sure you tell the interviewer that you are brainstorming possible solutions so that they are aware of your thought process.