[{"id": 1, "type": "short_answer", "skill": "multiplication", "question": "Calculate: 7 × 4", "difficulty": "medium", "explanation": "7 groups of 4.", "needs_review": false, "correct_answer": "28"}, {"id": 2, "type": "multiple_choice", "skill": "multiplication", "options": ["28", "24", "11", "35"], "question": "What is the product of 7 and 4?", "difficulty": "easy", "explanation": "7×4=28", "needs_review": false, "correct_answer": "28"}, {"id": 3, "type": "short_answer", "skill": "computation", "question": "Calculate: 14 × 9", "difficulty": "medium", "explanation": "Multiply: 14×9=126", "needs_review": false, "correct_answer": "126"}, {"id": 4, "type": "short_answer", "skill": "computation", "question": "Calculate: 18 × 8", "difficulty": "medium", "explanation": "Multiply: 18×8=144", "needs_review": false, "correct_answer": "144"}, {"id": 5, "type": "short_answer", "skill": "computation", "question": "Calculate: 14 × 5", "difficulty": "medium", "explanation": "Multiply: 14×5=70", "needs_review": false, "correct_answer": "70"}]