This paper reports on degrees of awareness and use of specific metacognitive strategies by 16 students in a final-year high school biology class in New Zealand. The aims of the intervention were to broaden students' thinking about bioethical issues associated with cancer and to enhance students' use of metacognition. Cues and prompts were used in this unit of work to help students use metacognitive strategies since students did not generally use metacognitive strategies spontaneously. Scaffolding was mediated through the teacher modelling, questioning, cueing or prompting students to evaluate their learning. The research reported here illustrates how teachers can cue students to be more self-directed in their learning. Three case studies illustrate how learning strategies were used differentially. Most students were aware of strategies that could help them to learn more effectively. It was found that those students who were not only aware of but also used strategies to plan, monitor and evaluate their work, produced essays of higher quality.