[{"id": 1, "type": "short_answer", "skill": "computation", "question": "Calculate: 43 + 21", "difficulty": "medium", "explanation": "Add systematically.", "needs_review": false, "correct_answer": "64"}, {"id": 2, "type": "multiple_choice", "skill": "properties", "options": ["Identity property", "Commutative property", "Associative property", "Distributive 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: 17 × 15", "difficulty": "medium", "explanation": "Multiply: 17×15=255", "needs_review": false, "correct_answer": "255"}, {"id": 4, "type": "short_answer", "skill": "computation", "question": "Calculate: 10 × 19", "difficulty": "medium", "explanation": "Multiply: 10×19=190", "needs_review": false, "correct_answer": "190"}, {"id": 5, "type": "short_answer", "skill": "computation", "question": "Calculate: 13 × 16", "difficulty": "medium", "explanation": "Multiply: 13×16=208", "needs_review": false, "correct_answer": "208"}, {"id": 6, "type": "short_answer", "skill": "computation", "question": "Calculate: 12 × 9", "difficulty": "medium", "explanation": "Multiply: 12×9=108", "needs_review": false, "correct_answer": "108"}, {"id": 7, "type": "short_answer", "skill": "computation", "question": "Calculate: 6 × 7", "difficulty": "medium", "explanation": "Multiply: 6×7=42", "needs_review": false, "correct_answer": "42"}, {"id": 8, "type": "short_answer", "skill": "computation", "question": "Calculate: 6 × 15", "difficulty": "medium", "explanation": "Multiply: 6×15=90", "needs_review": false, "correct_answer": "90"}]