[{"id": 1, "type": "short_answer", "skill": "computation", "question": "Calculate: 54 + 54", "difficulty": "medium", "explanation": "Add systematically.", "needs_review": false, "correct_answer": "108"}, {"id": 2, "type": "multiple_choice", "skill": "properties", "options": ["Commutative property", "Distributive property", "Identity 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: 19 × 5", "difficulty": "medium", "explanation": "Multiply: 19×5=95", "needs_review": false, "correct_answer": "95"}, {"id": 4, "type": "short_answer", "skill": "computation", "question": "Calculate: 5 × 20", "difficulty": "medium", "explanation": "Multiply: 5×20=100", "needs_review": false, "correct_answer": "100"}, {"id": 5, "type": "short_answer", "skill": "computation", "question": "Calculate: 18 × 15", "difficulty": "medium", "explanation": "Multiply: 18×15=270", "needs_review": false, "correct_answer": "270"}]