grading.md

Grading Rules

The grading engine is deterministic and stores both the raw answer and the normalized answer.

Answer Types

• exact: string comparison after trimming and spacing normalization.
• integer: integer numeric comparison.
• decimal: decimal numeric comparison with tolerance.
• fraction: rational equivalence, so 3/6 equals 1/2.
• set: unordered collection of values. 1, 2 is equivalent to 2; 1. Useful for problems with multiple answers.
• multiple: any answer in the list of acceptedAnswers is correct (e.g., choice A or B).
• multiple_choice: two to 20 visible options; the exact, case-sensitive stored option selected by the student is graded. Choices may contain LaTeX and safe problem image tokens. This is distinct from multiple, which is a free-response field with alternative accepted answers.
• expression: numeric evaluation. The system calculates the numeric value of the answerKey and compares it to the value of the student's input.
  • Equivalency: 0.5 matches 1/2. sqrt(2) matches 2^0.5.
  • Implicit Math: 2pi is recognized as 2 * pi.
  • Functions: Supports sin, cos, tan, ln, log, etc.

Normalization

• Trim leading and trailing whitespace.
• Collapse repeated whitespace.
• Normalize case unless the problem is case-sensitive.
• Preserve the original raw answer in the response record.
• Normalize equivalent fractions for fraction answers.
• Sort unordered values for set answers.

Regrading

When an admin edits an answer key or accepted answers, the system should:

1. Create an audit record.
2. Regrade affected responses.
3. Update attempt totals.
4. Notify students if a score changed.