[{"id": 1, "type": "short_answer", "skill": "computation", "question": "Calculate: 90 + 40", "difficulty": "medium", "explanation": "Add systematically.", "needs_review": false, "correct_answer": "130"}, {"id": 2, "type": "multiple_choice", "skill": "properties", "options": ["Associative property", "Distributive property", "Identity property", "Commutative 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: 10 × 6", "difficulty": "medium", "explanation": "Multiply: 10×6=60", "needs_review": false, "correct_answer": "60"}, {"id": 4, "type": "short_answer", "skill": "computation", "question": "Calculate: 20 × 7", "difficulty": "medium", "explanation": "Multiply: 20×7=140", "needs_review": false, "correct_answer": "140"}, {"id": 5, "type": "short_answer", "skill": "computation", "question": "Calculate: 11 × 14", "difficulty": "medium", "explanation": "Multiply: 11×14=154", "needs_review": false, "correct_answer": "154"}]