Chemistry Collective, 9-12

http://www.chemcollective.org/
This is a collection of virtual labs, scenario-based learning activities, and concepts tests that can be incorporated into a variety of teaching approaches as pre-labs, alternatives to textbook homework, and in-class activities for individuals or teams. It is organized by a group of faculty and staff at Carnegie Mellon University for teachers who are interested in using, assessing, and creating engaging online activities for chemistry education. The National Science Foundation currently funds it, so the software is available free of charge to all educators and students.