High school students studying chemistry confront a novel challenge. For most, chemistry is the first subject area in which they try to systematically understand natural phenomena they cannot directly observe. Although the material tools of chemistry investigation--e.g., various solids and liquid reagents, assortments of test tubes and glassware--populate students' laboratory experiences in chemistry class, the goal of chemistry education centers on the molecular phenomena underlying the manifest phenomena students encounter. But the very representations on which students must rely in order to engage with the concepts of the discipline prove to be difficult for students to use and understand. Chemical representations, therefore, are both an aid and an impediment to student understanding.

The goal of the ChemSense project is to help students overcome their difficulties in understanding chemical concepts by providing students access to rich representational tools that can fill a gap in their ability to experience or imagine the world of molecular entities and reactions. The ChemSense project is funded by the National Science Foundation, and our partners include the University of Michigan and California high schools. Together, we are developing software and activities to help students investigate chemical phenomena and express their understanding in a variety of chemistry representations. Our research documents student learning, changes in students' representational and discursive practices, and teacher implementation strategies.

The ChemSense Studio software offers distinct functionalities that enable students to create their own representations of chemical phenomena. The environment allows students to generate drawings, animations, text, and graphs. Specialized tools within the environment make it easy to create images of nanoscopic entities and processes. Students' ability to readily generate representations at the nanoscopic level helps them to move from simply depicting surface features of chemical phenomena to representing underlying phenomena that align with surface features. (See sample student work.)

Classroom activities designed by our partner teachers scaffold student use of interconnected forms of visual and discursive representations to enable students to describe, explain, and argue about the chemical experiments they are conducting on the lab bench. The commenting feature of the ChemSense Studio allows students to add textual annotations to visual representations and provides a ready means for discussion and commentary by students on one another's work, thereby further supporting the possibility for students to collectively arrive at new understandings of scientific concepts.

In sum, ChemSense tools and pedagogical approaches are intended to help students traverse the bridge between what they can see and the unseen, underlying processes that drive chemical reactions. Our analysis of this learning process focuses on the role of ChemSense in enabling two important and interrelated lines of development: chemical understanding and the reflective use of a variety of representations ("representational competence").