[{"id": 1, "type": "short_answer", "skill": "multiplication", "question": "Calculate: 6 × 4", "difficulty": "medium", "explanation": "6 groups of 4.", "needs_review": false, "correct_answer": "24"}, {"id": 2, "type": "multiple_choice", "skill": "multiplication", "options": ["20", "24", "10", "30"], "question": "What is the product of 6 and 4?", "difficulty": "easy", "explanation": "6×4=24", "needs_review": false, "correct_answer": "24"}, {"id": 3, "type": "short_answer", "skill": "computation", "question": "Calculate: 14 × 18", "difficulty": "medium", "explanation": "Multiply: 14×18=252", "needs_review": false, "correct_answer": "252"}, {"id": 4, "type": "short_answer", "skill": "computation", "question": "Calculate: 16 × 11", "difficulty": "medium", "explanation": "Multiply: 16×11=176", "needs_review": false, "correct_answer": "176"}, {"id": 5, "type": "short_answer", "skill": "computation", "question": "Calculate: 16 × 3", "difficulty": "medium", "explanation": "Multiply: 16×3=48", "needs_review": false, "correct_answer": "48"}]