[{"id": 1, "type": "short_answer", "skill": "subtraction", "question": "Calculate: 854 − 526", "difficulty": "medium", "explanation": "Subtract by place value, borrowing as needed.", "needs_review": false, "correct_answer": "328"}, {"id": 2, "type": "multiple_choice", "skill": "subtraction", "options": ["329", "326", "328", "1380"], "question": "What is 854 − 526?", "difficulty": "easy", "explanation": "854-526=328", "needs_review": false, "correct_answer": "328"}, {"id": 3, "type": "short_answer", "skill": "computation", "question": "Calculate: 8 × 2", "difficulty": "medium", "explanation": "Multiply: 8×2=16", "needs_review": false, "correct_answer": "16"}, {"id": 4, "type": "short_answer", "skill": "computation", "question": "Calculate: 9 × 14", "difficulty": "medium", "explanation": "Multiply: 9×14=126", "needs_review": false, "correct_answer": "126"}, {"id": 5, "type": "short_answer", "skill": "computation", "question": "Calculate: 19 × 6", "difficulty": "medium", "explanation": "Multiply: 19×6=114", "needs_review": false, "correct_answer": "114"}]