This is a traditional type of assessment in which a student draws a question/topic from a pool of possible questions, and gives an oral presentation immediately hereafter. The list of questions/topics can either be known or unknown.
Oral assessment without preparation time requires memorisation of basic terms and a wide knowledge of the entire curriculum. At the same time it allows for follow-up questions, which can, potentially, test a deeper understanding and clarify an unclear phrasing.
Oral assessments test communication skills, it is therefore recommended that students practice and receive feedback on their communication skills during the course.