Recipe

Recipe: Essay grader with rubric

Build a prompt that grades student essays against a custom rubric, returns structured scores, and explains each mark.

Ingredients

  • A rubric with 3–5 criteria and point ranges
  • One or more student essays (plain text)
  • System prompt that enforces JSON output
  • Temperature set to 0 for deterministic grading

Steps

  1. Define the rubric. List each criterion with its max points and a short description of what top marks look like.
  2. Write the system prompt. Instruct the model to return a JSON object with a scores array and a total field.
  3. Attach the essay. Pass the student text as a user message alongside the rubric.
  4. Parse the JSON. Extract scores, validate against rubric max points, and display per-criterion feedback.

Example prompt

You are an essay grader. Grade the essay below
against this rubric:

- Thesis clarity (0–10)
- Evidence quality (0–10)
- Organization (0–10)
- Grammar & style (0–10)

Return ONLY valid JSON:
{
  "scores": [
    { "criterion": "...", "score": N, "max": N, "comment": "..." }
  ],
  "total": N
}

Notes

  • Use temperature 0 for consistent, repeatable grades.
  • Validate the JSON schema before showing results to students.
  • For large classes, batch essays and process asynchronously.
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