[{"id": 1, "type": "short_answer", "skill": "computation", "question": "Calculate: 51 + 17", "difficulty": "medium", "explanation": "Add systematically.", "needs_review": false, "correct_answer": "68"}, {"id": 2, "type": "multiple_choice", "skill": "properties", "options": ["Associative property", "Identity property", "Commutative property", "Distributive property"], "question": "Which property states a+0=a?", "difficulty": "easy", "explanation": "The identity property of addition states that adding 0 to any number gives that number.", "needs_review": false, "correct_answer": "Identity property"}, {"id": 3, "type": "short_answer", "skill": "computation", "question": "Calculate: 4 × 7", "difficulty": "medium", "explanation": "Multiply: 4×7=28", "needs_review": false, "correct_answer": "28"}, {"id": 4, "type": "short_answer", "skill": "computation", "question": "Calculate: 12 × 8", "difficulty": "medium", "explanation": "Multiply: 12×8=96", "needs_review": false, "correct_answer": "96"}, {"id": 5, "type": "short_answer", "skill": "computation", "question": "Calculate: 16 × 12", "difficulty": "medium", "explanation": "Multiply: 16×12=192", "needs_review": false, "correct_answer": "192"}, {"id": 6, "type": "short_answer", "skill": "computation", "question": "Calculate: 9 × 9", "difficulty": "medium", "explanation": "Multiply: 9×9=81", "needs_review": false, "correct_answer": "81"}, {"id": 7, "type": "short_answer", "skill": "computation", "question": "Calculate: 18 × 11", "difficulty": "medium", "explanation": "Multiply: 18×11=198", "needs_review": false, "correct_answer": "198"}, {"id": 8, "type": "short_answer", "skill": "computation", "question": "Calculate: 17 × 4", "difficulty": "medium", "explanation": "Multiply: 17×4=68", "needs_review": false, "correct_answer": "68"}, {"id": 9, "type": "short_answer", "skill": "computation", "question": "Calculate: 16 × 17", "difficulty": "medium", "explanation": "Multiply: 16×17=272", "needs_review": false, "correct_answer": "272"}, {"id": 10, "type": "short_answer", "skill": "computation", "question": "Calculate: 18 × 12", "difficulty": "medium", "explanation": "Multiply: 18×12=216", "needs_review": false, "correct_answer": "216"}, {"id": 11, "type": "short_answer", "skill": "computation", "question": "Calculate: 18 × 18", "difficulty": "medium", "explanation": "Multiply: 18×18=324", "needs_review": false, "correct_answer": "324"}, {"id": 12, "type": "short_answer", "skill": "computation", "question": "Calculate: 16 × 18", "difficulty": "medium", "explanation": "Multiply: 16×18=288", "needs_review": false, "correct_answer": "288"}]