[{"id": 1, "type": "short_answer", "skill": "addition", "question": "Calculate: 50 + 50", "difficulty": "medium", "explanation": "Add by place value, regrouping as needed.", "needs_review": false, "correct_answer": "100"}, {"id": 2, "type": "multiple_choice", "skill": "addition", "options": ["99", "110", "100", "105"], "question": "What is the sum of 50 and 50?", "difficulty": "easy", "explanation": "50+50=100", "needs_review": false, "correct_answer": "100"}, {"id": 3, "type": "true_false", "skill": "properties", "question": "The commutative property means 50+50 = 50+50.", "difficulty": "easy", "explanation": "The commutative property states changing the order of addends does not change the sum.", "needs_review": false, "correct_answer": "True"}, {"id": 4, "type": "short_answer", "skill": "computation", "question": "Calculate: 20 × 9", "difficulty": "medium", "explanation": "Multiply: 20×9=180", "needs_review": false, "correct_answer": "180"}, {"id": 5, "type": "short_answer", "skill": "computation", "question": "Calculate: 4 × 19", "difficulty": "medium", "explanation": "Multiply: 4×19=76", "needs_review": false, "correct_answer": "76"}, {"id": 6, "type": "short_answer", "skill": "computation", "question": "Calculate: 2 × 9", "difficulty": "medium", "explanation": "Multiply: 2×9=18", "needs_review": false, "correct_answer": "18"}, {"id": 7, "type": "short_answer", "skill": "computation", "question": "Calculate: 14 × 3", "difficulty": "medium", "explanation": "Multiply: 14×3=42", "needs_review": false, "correct_answer": "42"}, {"id": 8, "type": "short_answer", "skill": "computation", "question": "Calculate: 3 × 8", "difficulty": "medium", "explanation": "Multiply: 3×8=24", "needs_review": false, "correct_answer": "24"}]