Practical work is widely seen as an integral part of school science. Research and teacher guidance have tended to consider practical work in science, rather than in individual science subjects or topics. This study used a questionnaire of selected- and open-response items to probe the views and reasoning of a sample of 43 pre-service teachers in England about the considerations that influence their use of practical work. Responses indicated a strongly positive view of the value of practical work to support a range of learning outcomes. A majority of respondents thought that the usefulness of practical work varies across topics due to differences in what can be directly observed and in potential to challenge learners' ideas. Responses showed awareness of the key role of practical work in linking observations and ideas, but also highlighted challenges in applying broad principles about practical work to content-specific examples and a limited awareness of the range of possible types of practical activity. The study supports the view that researchers and advocates of practical work should engage with issues at a smaller grain size than hitherto in order to gain a better understanding of teachers' decision-making and enable more effective classroom practices.