[{"id": 1, "type": "short_answer", "skill": "computation", "question": "Calculate: 20 + 54", "difficulty": "medium", "explanation": "Add systematically.", "needs_review": false, "correct_answer": "74"}, {"id": 2, "type": "multiple_choice", "skill": "properties", "options": ["Identity property", "Commutative property", "Associative 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: 15 × 16", "difficulty": "medium", "explanation": "Multiply: 15×16=240", "needs_review": false, "correct_answer": "240"}, {"id": 4, "type": "short_answer", "skill": "computation", "question": "Calculate: 15 × 20", "difficulty": "medium", "explanation": "Multiply: 15×20=300", "needs_review": false, "correct_answer": "300"}, {"id": 5, "type": "short_answer", "skill": "computation", "question": "Calculate: 2 × 13", "difficulty": "medium", "explanation": "Multiply: 2×13=26", "needs_review": false, "correct_answer": "26"}, {"id": 6, "type": "short_answer", "skill": "computation", "question": "Calculate: 19 × 16", "difficulty": "medium", "explanation": "Multiply: 19×16=304", "needs_review": false, "correct_answer": "304"}, {"id": 7, "type": "short_answer", "skill": "computation", "question": "Calculate: 4 × 4", "difficulty": "medium", "explanation": "Multiply: 4×4=16", "needs_review": false, "correct_answer": "16"}, {"id": 8, "type": "short_answer", "skill": "computation", "question": "Calculate: 12 × 13", "difficulty": "medium", "explanation": "Multiply: 12×13=156", "needs_review": false, "correct_answer": "156"}]