[{"id": 1, "type": "short_answer", "skill": "computation", "question": "Calculate: 91 + 30", "difficulty": "medium", "explanation": "Add systematically.", "needs_review": false, "correct_answer": "121"}, {"id": 2, "type": "multiple_choice", "skill": "properties", "options": ["Distributive property", "Commutative 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: 7 × 19", "difficulty": "medium", "explanation": "Multiply: 7×19=133", "needs_review": false, "correct_answer": "133"}, {"id": 4, "type": "short_answer", "skill": "computation", "question": "Calculate: 13 × 11", "difficulty": "medium", "explanation": "Multiply: 13×11=143", "needs_review": false, "correct_answer": "143"}, {"id": 5, "type": "short_answer", "skill": "computation", "question": "Calculate: 5 × 4", "difficulty": "medium", "explanation": "Multiply: 5×4=20", "needs_review": false, "correct_answer": "20"}]