This paper describes a study which investigated 14 and 15 year old students' understanding of combustion in both England and Spain, and explores the effect of practical laboratory experience on students' understanding. The teaching and learning styles used with the students in the study were explored using questionnaires and interviews. The students' understanding of combustion was explored using a questionnaire. The responses of English and Spanish students are significantly different. The quality of the responses is explored in terms of the awareness of students of the involvement of gases in combustion, and it appears, however, that the more extensive use of practical work in English schools has had only a marginal effect on their understanding of combustion.