This paper draws on earlier work on ideas that underpin the collection and use of evidence in science in schools. It establishes that different types of practical work share the same procedural underpinnings. It then takes the work of Toulmin on argumentation to suggest that the idea of the "public claim" can be used to forge a link between scientific experimentation in schools and emerging ideas of scientific literacy. It concludes with a discussion of possible implications. (Contains 4 tables, 7 figures, and 6 notes.)