[{"id": 1, "type": "short_answer", "skill": "computation", "question": "Calculate: 66 + 27", "difficulty": "medium", "explanation": "Add systematically.", "needs_review": false, "correct_answer": "93"}, {"id": 2, "type": "multiple_choice", "skill": "properties", "options": ["Commutative property", "Identity property", "Distributive property", "Associative 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: 13 × 6", "difficulty": "medium", "explanation": "Multiply: 13×6=78", "needs_review": false, "correct_answer": "78"}, {"id": 4, "type": "short_answer", "skill": "computation", "question": "Calculate: 18 × 7", "difficulty": "medium", "explanation": "Multiply: 18×7=126", "needs_review": false, "correct_answer": "126"}, {"id": 5, "type": "short_answer", "skill": "computation", "question": "Calculate: 9 × 7", "difficulty": "medium", "explanation": "Multiply: 9×7=63", "needs_review": false, "correct_answer": "63"}]