The roles of representations and tools in the chemistry laboratory and their implications for chemistry learning

In this historical and observational study, we describe how scientists use representations and tools in the chemistry laboratory, and we derive implic ations from these findings for the design of educational environments. In o ur observations we found that chemists use representations and tools to med iate between the physical substances that they study and the aperceptual ch emical entities and processes that underlie and account for the material qu alities of these physical substances. There are 2 important, interrelated a spects of this mediational process: the material and the social. The Ist em phasizes the surface features of both physical phenomena and symbolic repre sentations, features that can be perceived and manipulated. The 2nd undersc ores the inherently semiotic, rhetorical process whereby chemists claim tha t representations stand for unseen entities and processes. In elaborating o n our analyses, we Examine the historical origins and contemporary practices of representation use in one particular domain-chemistry-to look at how developments in the design of representations advance the development of a scientific community , as well as the understanding of scientists engaged in laboratory practice . Examine representations spontaneously generated by chemists, as well as tho se generated by their tools or instruments, and look at how scientists-indi vidually and collaboratively-coordinate these 2 types of representations wi th the material substances of their investigations to understand the struct ures and processes that underlie them. Draw implications from the study of scientists to make recommendations for the design of learning environments and symbol systems that can support the use of representations by students to understand the structures and proces ses that underlie their scientific investigations and to engage them in the practices of knowledge-building communities.