A case study of a final year high school biology class in New Zealand is used to illustrate how the New Zealand assessment system allows students to demonstrate the knowledge, attributes and skills considered to be important in learning about bioethical issues. The New Zealand achievement standard system is briefly described. In this case, students were assessed by an essay (500 words) in an external exam. Self and peer assessment activities as well as a range of self-monitoring strategies were used to help students to improve their practice essays. Some of the problems highlighted in this study indicate that teachers need to emphasise what is required of students in more detail and they need to provide multiple opportunities for students to develop the skills of self-questioning, independent inquiry, critical thinking and essay writing.