Authoring Problem-Solving Tutors: A Comparison between ASTUS and CTAT

Luc Paquette, Jean François Lebeau, André Mayers

Research output: Chapter in Book/Report/Conference proceedingChapter


ASTUS is an Intelligent Tutoring System (ITS) framework for problem-solving domains. In this chapter we present a study we performed to evaluate the strengths and weaknesses of ASTUS compared to the well-known Cognitive Tutor Authoring Tools (CTAT) framework. To challenge their capacity to handle a comprehensive model of a well-defined task, we built a multi-column subtraction tutor (model and interface) with each framework. We incorporated into the model various pedagogically relevant procedural errors taken from the literature, to see how each framework deals with complex situations where remedial help may be needed. We successfully encoded the model with both frameworks and found situations in which we consider ASTUS to surpass CTAT. Examples of these include: ambiguous steps, errors with multiple (possibly correct) steps, composite errors, and off-path steps. Selected scenarios in the multi-column subtraction domain are presented to illustrate that ASTUS can show a more sophisticated behavior in these situations. ASTUS achieves this by relying on an examinable hierarchical knowledge representation system and a domain-independent MVC-based approach to build the tutors' interface.

Original languageEnglish (US)
Title of host publicationAdvances in Intelligent Tutoring Systems
EditorsRoger Nkambou, Jacqueline Bourdeau, Riichirio Mizoguchi
PublisherSpringer-Verlag Berlin Heidelberg
Number of pages29
ISBN (Print)9783642143625
StatePublished - Oct 6 2010
Externally publishedYes

Publication series

NameStudies in Computational Intelligence
ISSN (Print)1860-949X


  • production rule
  • procedural knowledge
  • correct step
  • intelligent tutor system
  • pedogogical interaction

ASJC Scopus subject areas

  • Artificial Intelligence

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  • Cite this

    Paquette, L., Lebeau, J. F., & Mayers, A. (2010). Authoring Problem-Solving Tutors: A Comparison between ASTUS and CTAT. In R. Nkambou, J. Bourdeau, & R. Mizoguchi (Eds.), Advances in Intelligent Tutoring Systems (pp. 377-405). (Studies in Computational Intelligence; Vol. 308). Springer-Verlag Berlin Heidelberg.