[{"id": 1, "type": "short_answer", "skill": "multiplication", "question": "Calculate: 7 × 9", "difficulty": "medium", "explanation": "7 groups of 9.", "needs_review": false, "correct_answer": "63"}, {"id": 2, "type": "multiple_choice", "skill": "multiplication", "options": ["70", "54", "16", "63"], "question": "What is the product of 7 and 9?", "difficulty": "easy", "explanation": "7×9=63", "needs_review": false, "correct_answer": "63"}, {"id": 3, "type": "short_answer", "skill": "computation", "question": "Calculate: 6 × 9", "difficulty": "medium", "explanation": "Multiply: 6×9=54", "needs_review": false, "correct_answer": "54"}, {"id": 4, "type": "short_answer", "skill": "computation", "question": "Calculate: 4 × 13", "difficulty": "medium", "explanation": "Multiply: 4×13=52", "needs_review": false, "correct_answer": "52"}, {"id": 5, "type": "short_answer", "skill": "computation", "question": "Calculate: 5 × 7", "difficulty": "medium", "explanation": "Multiply: 5×7=35", "needs_review": false, "correct_answer": "35"}, {"id": 6, "type": "short_answer", "skill": "computation", "question": "Calculate: 6 × 15", "difficulty": "medium", "explanation": "Multiply: 6×15=90", "needs_review": false, "correct_answer": "90"}, {"id": 7, "type": "short_answer", "skill": "computation", "question": "Calculate: 7 × 15", "difficulty": "medium", "explanation": "Multiply: 7×15=105", "needs_review": false, "correct_answer": "105"}, {"id": 8, "type": "short_answer", "skill": "computation", "question": "Calculate: 18 × 14", "difficulty": "medium", "explanation": "Multiply: 18×14=252", "needs_review": false, "correct_answer": "252"}]