Cognitive Tutor Authoring Tools 2.0 > CTAT Basics > Tutor Types

3. Tutor Types

CTAT enables you to create two main types of tutors: Example-tracing Tutors, which can be created without programming, but require problem-specific authoring; and Cognitive Tutors, which require building a cognitive model of student problem solving, but support tutoring across a range of similar problems.

There are a few factors that may influence your decision regarding which tutor type to build:

If you are new to the process of creating a tutor, we recommend that you start with an Example-tracing Tutor.

For more information on the different types of tutors, see the Tutor Types page on the CTAT web site.

3.1. Example-tracing Tutor

An Example-tracing tutor is based on a single problem representation stored in a behavior graph (BRD, or behavior recorder data, file). You create this graph by demonstrating problem-solving steps with the student interface. (See Example-tracing Tutors for more on creating an Example-tracing Tutor.)

By default, the following tools are shown when the Example-tracing Tutor type is selected:

  • Behavior Recorder

The Behavior Recorder is the only tool required to create an Example-tracing Tutor. In addition, you will need a student interface (built in Java or Flash) in which to demonstrate behavior. In the Behavior Recorder, you can generalize, annotate, and test you graph.

3.2. Cognitive Tutor (Jess)

A Cognitive Tutor is based on a rule-based cognitive model of student problem-solving knowledge (modeled in Jess). This cognitive model is commonly applicable to various problems in the same domain. You create a cognitive model by writing production rules that characterize the variety of strategies and misconceptions students may acquire. (Cognitive Tutors are sometimes are also called "Production Rule Tutors", a reference to the production rules you create when modeling.)

During problem solving, the Cognitive Tutor follows the student in a process called model-tracing. In model-tracing, the tutoring system maintains a model of problem solving that is 'traced' (compared) against the student's actions. Feedback during problem-solving is given based on current state of the model (also called working memory) and the rules that represent student cognition and action.

By default, the following tools are shown the Cognitive Tutor (Jess) type is selected:

  • Behavior Recorder

  • Conflict Tree

  • WME Editor

  • Jess Console

These tools are explained in detail in the section Cognitive Tutor (Jess) Tools.

3.3. Cognitive Tutor (TDK)


The Cognitive Tutor (TDK) tutor type is not supported in CTAT 2.0.

A Cognitive Tutor (TDK) is a tutor based on the TDK (Tutor Development Kit) production rule language. This tutor type requires access to a LISP rule engine, which is not included with CTAT.

The TDK modeling language was used to develop the Algebra and Geometry Cognitive Tutors.

3.4. Simulated Student

Simulated Student, or Sim St, is a CTAT module that learns cognitive skills from model solutions demonstrated by human problem-solvers.

Using Sim St, an author demonstrates solutions to problems in a domain using a student interface connected to CTAT. The Simulated Student observes those demonstrations and generates a set of Jess production rules that replicate the problem-solving steps demonstrated. These production rules are generalizations of the observed behavior. If these generalizations are correct—i.e., are correct implementations of the actual task that is being taught—then they can be added to the cognitive model as correct rules. If the generalizations are incorrect but "plausible" (in the sense that a student might adopt the incorrect conception), then they can be added to the cognitive model as buggy rules. Both correct and buggy rules would form the cognitive model of a Cognitive Tutor, allowing the tutor to perform its usual functions, namely, model tracing and scaffolding.

Access to Simulated Student functions can be found on the CTAT menu Sim. St.

More information on Simulated Student can be found at the project home page,

Tutorials on using Sim. St can be found on the CTAT Tutorials page.