Data were gathered from 95 Year 10 students in a New Zealand secondary school to explore how the indicators of scientific literacy are expressed in student responses. These students completed an activity based around the two contexts of lighting and health. A matrix, which incorporated descriptive indicators, was developed to analyse the student responses and revealed levels of expression of scientific literacy. Use of this matrix enabled a fine-grained analysis of both group and individual student expressions of scientific literacy. It was found that students' express scientific literacy in complex ways and that they can exhibit multiple levels simultaneously, both within and between contexts.