Open Answer

Free text answer. Evaluated by character similarity or minimum length.

With correctAnswer (Levenshtein similarity)

Texts are truncated to 500 characters for calculation.

Feedback	Condition
"Good answer!" + correct: true, score 8-10	similarity >= 0.8
"Your answer is partially correct." + correct: false, score 5-7	0.5 <= sim < 0.8
"Incorrect. Review the topic and try again." + correct: false, score 0-4	similarity < 0.5

{
  "exerciseId": "ex_003",
  "area": "writing",
  "type": "open_answer",
  "answer": "The cat is sleeping on the couch",
  "correctAnswer": "The cat sleeps on the sofa"
}

{
  "correct": false,
  "score": 7,
  "feedback": "Your answer is partially correct. Try to be more precise.",
  "metadata": { "area": "writing", "type": "open_answer" }
}

Without correctAnswer (minimum length)

Feedback	Condition
"Answer received." + correct: true, score 10	length >= 10 characters
"Answer too short." + correct: false, score 0	length < 10 characters

{
  "exerciseId": "ex_003b",
  "area": "writing",
  "type": "open_answer",
  "answer": "I think dogs are loyal companions to humans."
}

Without correctAnswer, only checks that the user wrote something meaningful. For quality evaluation, always include correctAnswer.