Cognitive Tutor for Order of Operations and Evaluation of C Expression

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Cognitive Tutor for Order of Operations and
Evaluation of C Expression

• Cognitive Modeling and
• Intelligent Tutoring Systems

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Introduction

• What?
• Cognitive tutor for order of operation and
  Evaluation of C expressions.
• Why?
• Help students learn C expression.
• Help the human instructor focus on other aspects
  of programming like designing a program.
• Who?
• Students learning C as their first programming
  language.

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Difficulty Factors

• Sample 1
• f--c--d-e
• 1 4 2 5 6 3
• Sample 2
• x / y a b
• 1 2 3

We restricted DFA to a partial set of C operators
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Student Solution

• Sample 1
• f--c--d-e
• 1 4 2 5 6 3
• Sample 2
• x / y a b
• 1 2 3

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Insights

• Students learn order of operations and understand
  the operators simultaneously.
• Finding order of operation and evaluation of the
  operator are not independent steps while
  evaluating the expression.

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The Model

• What we planned
• Perform lexical analysis of the given expression
  to distinguish between operators and operands.
• Apply production rules to determine the
  current-operation.
• Apply production rules to evaluate the current
  operation.
• What we did
• Use solution tree for ordering of operations.
• Determine current operator using production rules
  and predefined solution tree.
• Evaluate the current operation using production
  rules.

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The Model

• Drawbacks of the implementation
• Solution trees
• are not generic
• are not consistent with the cognitive model of
  expert user
• Lead to incorrect parsing of some problems7 / 4
  5 5 3 - 6
• Ignored special cases like zero.
• Students do not evaluate 0a or 0a

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The Tutor

• Interface

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The Tutor

• Problem 1

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The Tutor

• Problem 1
• Hint 1 for Step 1

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The Tutor

• Problem 1
• Hint 2 for Step 1

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The Tutor

• Problem 1
• Hint 3 for Step 1

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The Tutor

• Problem 1
• Done

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The Tutor

• Problem 1
• Behavior recorder trace

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The Tutor

• Problem 2

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The Tutor

• Problem 2
• Buggy message 1 (for int v/s float / )

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The Tutor

• Problem 2
• Buggy message 2 (for and sequence)

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Questions?