[{"id": 1, "type": "short_answer", "skill": "computation", "question": "Calculate: 42 + 68", "difficulty": "medium", "explanation": "Add systematically.", "needs_review": false, "correct_answer": "110"}, {"id": 2, "type": "multiple_choice", "skill": "properties", "options": ["Commutative property", "Associative property", "Distributive property", "Identity 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: 20 × 12", "difficulty": "medium", "explanation": "Multiply: 20×12=240", "needs_review": false, "correct_answer": "240"}, {"id": 4, "type": "short_answer", "skill": "computation", "question": "Calculate: 4 × 18", "difficulty": "medium", "explanation": "Multiply: 4×18=72", "needs_review": false, "correct_answer": "72"}, {"id": 5, "type": "short_answer", "skill": "computation", "question": "Calculate: 16 × 19", "difficulty": "medium", "explanation": "Multiply: 16×19=304", "needs_review": false, "correct_answer": "304"}, {"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 × 13", "difficulty": "medium", "explanation": "Multiply: 7×13=91", "needs_review": false, "correct_answer": "91"}, {"id": 8, "type": "short_answer", "skill": "computation", "question": "Calculate: 15 × 16", "difficulty": "medium", "explanation": "Multiply: 15×16=240", "needs_review": false, "correct_answer": "240"}]