As your mentee learns and applies the negotiation skills, you can give them constructive feedback to help them improve. You can use the SBI model, which stands for situation, behavior, and impact, to structure your feedback. You can describe the specific situation where your mentee used a negotiation skill, the behavior they exhibited, and the impact it had on the outcome. You can also use the STAR model, which stands for situation, task, action, and result, to help your mentee reflect on their own performance. You can ask them to describe the situation where they had to negotiate, the task they had to accomplish, the action they took, and the result they achieved. You can then praise their strengths, suggest areas for improvement, and offer tips and resources for further learning.