[{"id": 1, "type": "short_answer", "skill": "area", "question": "Find the area of a rectangle: length=12, width=6", "difficulty": "medium", "explanation": "A=l×w=12×6=72 sq units.", "needs_review": false, "correct_answer": "72"}, {"id": 2, "type": "multiple_choice", "skill": "perimeter", "options": ["18", "36", "48", "72"], "question": "Find the perimeter of a rectangle: length=12, width=6", "difficulty": "medium", "explanation": "P=2(l+w)=2(12+6)=2(18)=36", "needs_review": false, "correct_answer": "36"}, {"id": 3, "type": "short_answer", "skill": "computation", "question": "Calculate: 9 × 18", "difficulty": "medium", "explanation": "Multiply: 9×18=162", "needs_review": false, "correct_answer": "162"}, {"id": 4, "type": "short_answer", "skill": "computation", "question": "Calculate: 12 × 11", "difficulty": "medium", "explanation": "Multiply: 12×11=132", "needs_review": false, "correct_answer": "132"}, {"id": 5, "type": "short_answer", "skill": "computation", "question": "Calculate: 10 × 13", "difficulty": "medium", "explanation": "Multiply: 10×13=130", "needs_review": false, "correct_answer": "130"}, {"id": 6, "type": "short_answer", "skill": "computation", "question": "Calculate: 14 × 3", "difficulty": "medium", "explanation": "Multiply: 14×3=42", "needs_review": false, "correct_answer": "42"}, {"id": 7, "type": "short_answer", "skill": "computation", "question": "Calculate: 15 × 5", "difficulty": "medium", "explanation": "Multiply: 15×5=75", "needs_review": false, "correct_answer": "75"}, {"id": 8, "type": "short_answer", "skill": "computation", "question": "Calculate: 15 × 19", "difficulty": "medium", "explanation": "Multiply: 15×19=285", "needs_review": false, "correct_answer": "285"}]