The Virtual Molecular Dynamics Laboratory will revise a set of instructional materials for virtual chemistry laboratories and provide professional development on those materials to 336 high school chemistry teachers. A key feature of the materials is the use of molecular dynamics. Students can see in real time, the microscopic behavior and using split-screen software programs can simultaneously see the corresponding macroscopic behavior. By changing the system conditions (e.g., the temperature) the student can begin to understand both the microscopic and macroscopic properties. The teachers' professional development will focus on using the simulations in their classes, introducing the use of cooperative learning as a pedagogical approach to teaching chemistry and encouraging the teachers to contribute to their profession by developing new activities, approaches, lessons and assessments using the computer as a simulator.