[{"id": 1, "type": "short_answer", "skill": "computation", "question": "Calculate: 84 + 31", "difficulty": "medium", "explanation": "Add systematically.", "needs_review": false, "correct_answer": "115"}, {"id": 2, "type": "multiple_choice", "skill": "properties", "options": ["Commutative property", "Associative property", "Identity 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: 19 × 18", "difficulty": "medium", "explanation": "Multiply: 19×18=342", "needs_review": false, "correct_answer": "342"}, {"id": 4, "type": "short_answer", "skill": "computation", "question": "Calculate: 9 × 5", "difficulty": "medium", "explanation": "Multiply: 9×5=45", "needs_review": false, "correct_answer": "45"}, {"id": 5, "type": "short_answer", "skill": "computation", "question": "Calculate: 5 × 19", "difficulty": "medium", "explanation": "Multiply: 5×19=95", "needs_review": false, "correct_answer": "95"}, {"id": 6, "type": "short_answer", "skill": "computation", "question": "Calculate: 12 × 5", "difficulty": "medium", "explanation": "Multiply: 12×5=60", "needs_review": false, "correct_answer": "60"}, {"id": 7, "type": "short_answer", "skill": "computation", "question": "Calculate: 13 × 10", "difficulty": "medium", "explanation": "Multiply: 13×10=130", "needs_review": false, "correct_answer": "130"}, {"id": 8, "type": "short_answer", "skill": "computation", "question": "Calculate: 18 × 18", "difficulty": "medium", "explanation": "Multiply: 18×18=324", "needs_review": false, "correct_answer": "324"}]