The Cognitive Tutor Authoring Tools, or CTAT, is a tool suite that enables you to add learning by doing (i.e., active learning) to online courses. CTAT supports the creation of flexible tutors for both simple and complex problem solving, capable of supporting multiple strategies that students may draw on when solving tutor problems. CTAT tutors track students as they work through problems and provide context-sensitive, just-in-time help.
CTAT supports the creation of two types of tutors: example-tracing tutors, which can be created without programming but require problem-specific authoring, and Cognitive Tutors, which require AI programming to build a cognitive model of student problem solving but support tutoring across a range of problems. The two types of tutors are roughly behaviorally equivalent.
See the CTAT web-site. Vincent Aleven and Bruce McLaren are the PSLC researchers who lead the CTAT project. The following soon-to-be-published paper is the most extensive review of CTAT available, particularly focused on example-tracing tutors.
Aleven, V., McLaren, B.M., Sewall, J., and Koedinger, K. (under review). Example-Tracing Tutors: A New Paradigm for Intelligent Tutoring Systems. International Journal of Artificial Intelligence in Education.