This is one of the most interesting questions, as you would assume with every undergraduate degree, there would be formal exams. However, instead of exams, there are other modes of study and assessment. You willl gain academic knowledge and discipline through essay based writing, reports, debates, presentation work, case studies, critical analysis, research based writing.
I believe these forms of assessments prepare students for real life work and what Social Policy or any social science field is about. They engage students more into the practicality of the course and encourage them to develop creativity and discipline. You also gain understanding and expertise into the research field. These skills also help with further studies and employability within social science courses or jobs. By gaining these skills, you are a step closer to progression in your chosen sector/field.