Your responses to behavioral interview questions will take the S-T-A-R approach.
1. S or T - Describe the situation or task
2. A - Describe the action you took in the context of the situation or task
3. R- What was the result of your action.
As you can see from the comments, there's a lot of disagreement (some not so kind!) about whether this post has value. But I think it does: being able to explain, coherently, about a time you solved a problem or took an action that had a positive impact on your organization tells the employer how you might be able to solve problems at his or her workplace.