As Generative AI (GenAI) reshapes software engineering practice, there is a growing need to understand how it might support students in developing software requirements. In Agile software development, requirements are captured as small user stories describing a user need. We describe our experience in undergraduate software engineering courses of students using GenAI in the classroom to create user story requirements. Our approach was to teach students how to create quality requirements followed by an assessment of their skills. After practicing this skill, we then trained the students on the effective use of GenAI by discussing prompting techniques and the importance of analyzing AI responses applying their knowledge of quality requirements. In a final assessment, we asked the students to write user story requirements using GenAI as an assistant, applying these techniques. Because computer science students entering the workforce are likely to use AI tools in software engineering tasks, we examined whether guided use of GenAI improves student performance in writing user story requirements. Rather than treating GenAI as a teaching aid for eventual independent performance without AI, we focused on guiding students to learn to use it effectively as part of the requirements-writing process they may encounter in professional practice.