"Evaluative constructivism" is used to describe how students derived learning intentions and made choices about what they would do during a unit of work in a final-year high school biology class, as they conducted an inquiry into the social and ethical issues associated with cancer. The context of the study, theoretical background and overview of students' awareness of their learning strengths and needs are related to the level of achievement in the essays they wrote. The case studies illustrate the diversity in the extent of knowledge and use of learning strategies and the implications this has for the level of support teachers can provide to enable students to be more self-directed. The concepts outlined here have very wide application to multiple learning contexts.