The Cognitive Tutor Authoring Tools (CTAT) [1] are a suite of software programs meant to make the creation of web-based ITS practical for non-programmers. CTAT supports a relatively novel type of tutors, called example-tracing tutors, which use examples of problem-solving approaches to assess and guide students as they practice solving problems. CTAT employs a programming-by-demonstration paradigm that relies on creating examples of how problems are to be solved, rather than defining general rules or constraints that characterize solutions or solution processes. The result is an editable behavior graph that contains the tutor's intelligence about how to react to student actions and what hints to give for next steps. Although relatively easy to build, example-tracing tutors support the key behaviors identified by VanLehn [2] as characteristic of ITS. Data from over 26 research studies using CTAT indicate that these tools lower the cost of ITS development by a factor of 4-8.
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