[{"id": 1, "type": "short_answer", "skill": "area", "question": "Find the area of a rectangle: length=5, width=7", "difficulty": "medium", "explanation": "A=l×w=5×7=35 sq units.", "needs_review": false, "correct_answer": "35"}, {"id": 2, "type": "multiple_choice", "skill": "perimeter", "options": ["12", "24", "20", "35"], "question": "Find the perimeter of a rectangle: length=5, width=7", "difficulty": "medium", "explanation": "P=2(l+w)=2(5+7)=2(12)=24", "needs_review": false, "correct_answer": "24"}, {"id": 3, "type": "short_answer", "skill": "computation", "question": "Calculate: 15 × 9", "difficulty": "medium", "explanation": "Multiply: 15×9=135", "needs_review": false, "correct_answer": "135"}, {"id": 4, "type": "short_answer", "skill": "computation", "question": "Calculate: 19 × 16", "difficulty": "medium", "explanation": "Multiply: 19×16=304", "needs_review": false, "correct_answer": "304"}, {"id": 5, "type": "short_answer", "skill": "computation", "question": "Calculate: 12 × 3", "difficulty": "medium", "explanation": "Multiply: 12×3=36", "needs_review": false, "correct_answer": "36"}]