[{"id": 1, "type": "short_answer", "skill": "area", "question": "Find the area of a rectangle: length=6, width=3", "difficulty": "medium", "explanation": "A=l×w=6×3=18 sq units.", "needs_review": false, "correct_answer": "18"}, {"id": 2, "type": "multiple_choice", "skill": "perimeter", "options": ["24", "9", "18", "18"], "question": "Find the perimeter of a rectangle: length=6, width=3", "difficulty": "medium", "explanation": "P=2(l+w)=2(6+3)=2(9)=18", "needs_review": false, "correct_answer": "18"}, {"id": 3, "type": "short_answer", "skill": "computation", "question": "Calculate: 19 × 7", "difficulty": "medium", "explanation": "Multiply: 19×7=133", "needs_review": false, "correct_answer": "133"}, {"id": 4, "type": "short_answer", "skill": "computation", "question": "Calculate: 4 × 12", "difficulty": "medium", "explanation": "Multiply: 4×12=48", "needs_review": false, "correct_answer": "48"}, {"id": 5, "type": "short_answer", "skill": "computation", "question": "Calculate: 9 × 16", "difficulty": "medium", "explanation": "Multiply: 9×16=144", "needs_review": false, "correct_answer": "144"}]