[{"id": 1, "type": "short_answer", "skill": "computation", "question": "Calculate: 31 + 73", "difficulty": "medium", "explanation": "Add systematically.", "needs_review": false, "correct_answer": "104"}, {"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: 14 × 2", "difficulty": "medium", "explanation": "Multiply: 14×2=28", "needs_review": false, "correct_answer": "28"}, {"id": 4, "type": "short_answer", "skill": "computation", "question": "Calculate: 15 × 16", "difficulty": "medium", "explanation": "Multiply: 15×16=240", "needs_review": false, "correct_answer": "240"}, {"id": 5, "type": "short_answer", "skill": "computation", "question": "Calculate: 15 × 12", "difficulty": "medium", "explanation": "Multiply: 15×12=180", "needs_review": false, "correct_answer": "180"}, {"id": 6, "type": "short_answer", "skill": "computation", "question": "Calculate: 20 × 9", "difficulty": "medium", "explanation": "Multiply: 20×9=180", "needs_review": false, "correct_answer": "180"}, {"id": 7, "type": "short_answer", "skill": "computation", "question": "Calculate: 3 × 11", "difficulty": "medium", "explanation": "Multiply: 3×11=33", "needs_review": false, "correct_answer": "33"}, {"id": 8, "type": "short_answer", "skill": "computation", "question": "Calculate: 20 × 3", "difficulty": "medium", "explanation": "Multiply: 20×3=60", "needs_review": false, "correct_answer": "60"}]