[{"id": 1, "type": "short_answer", "skill": "area", "question": "Find the area of a rectangle: length=10, width=4", "difficulty": "medium", "explanation": "A=l×w=10×4=40 sq units.", "needs_review": false, "correct_answer": "40"}, {"id": 2, "type": "multiple_choice", "skill": "perimeter", "options": ["40", "40", "28", "14"], "question": "Find the perimeter of a rectangle: length=10, width=4", "difficulty": "medium", "explanation": "P=2(l+w)=2(10+4)=2(14)=28", "needs_review": false, "correct_answer": "28"}, {"id": 3, "type": "short_answer", "skill": "computation", "question": "Calculate: 9 × 4", "difficulty": "medium", "explanation": "Multiply: 9×4=36", "needs_review": false, "correct_answer": "36"}, {"id": 4, "type": "short_answer", "skill": "computation", "question": "Calculate: 20 × 13", "difficulty": "medium", "explanation": "Multiply: 20×13=260", "needs_review": false, "correct_answer": "260"}, {"id": 5, "type": "short_answer", "skill": "computation", "question": "Calculate: 17 × 9", "difficulty": "medium", "explanation": "Multiply: 17×9=153", "needs_review": false, "correct_answer": "153"}, {"id": 6, "type": "short_answer", "skill": "computation", "question": "Calculate: 13 × 12", "difficulty": "medium", "explanation": "Multiply: 13×12=156", "needs_review": false, "correct_answer": "156"}, {"id": 7, "type": "short_answer", "skill": "computation", "question": "Calculate: 14 × 4", "difficulty": "medium", "explanation": "Multiply: 14×4=56", "needs_review": false, "correct_answer": "56"}, {"id": 8, "type": "short_answer", "skill": "computation", "question": "Calculate: 16 × 18", "difficulty": "medium", "explanation": "Multiply: 16×18=288", "needs_review": false, "correct_answer": "288"}]