[{"id": 1, "type": "short_answer", "skill": "computation", "question": "Calculate: 75 + 21", "difficulty": "medium", "explanation": "Add systematically.", "needs_review": false, "correct_answer": "96"}, {"id": 2, "type": "multiple_choice", "skill": "properties", "options": ["Associative property", "Identity property", "Commutative 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: 19 × 5", "difficulty": "medium", "explanation": "Multiply: 19×5=95", "needs_review": false, "correct_answer": "95"}, {"id": 4, "type": "short_answer", "skill": "computation", "question": "Calculate: 6 × 12", "difficulty": "medium", "explanation": "Multiply: 6×12=72", "needs_review": false, "correct_answer": "72"}, {"id": 5, "type": "short_answer", "skill": "computation", "question": "Calculate: 9 × 18", "difficulty": "medium", "explanation": "Multiply: 9×18=162", "needs_review": false, "correct_answer": "162"}, {"id": 6, "type": "short_answer", "skill": "computation", "question": "Calculate: 14 × 6", "difficulty": "medium", "explanation": "Multiply: 14×6=84", "needs_review": false, "correct_answer": "84"}, {"id": 7, "type": "short_answer", "skill": "computation", "question": "Calculate: 13 × 15", "difficulty": "medium", "explanation": "Multiply: 13×15=195", "needs_review": false, "correct_answer": "195"}, {"id": 8, "type": "short_answer", "skill": "computation", "question": "Calculate: 13 × 12", "difficulty": "medium", "explanation": "Multiply: 13×12=156", "needs_review": false, "correct_answer": "156"}, {"id": 9, "type": "short_answer", "skill": "computation", "question": "Calculate: 2 × 7", "difficulty": "medium", "explanation": "Multiply: 2×7=14", "needs_review": false, "correct_answer": "14"}, {"id": 10, "type": "short_answer", "skill": "computation", "question": "Calculate: 15 × 10", "difficulty": "medium", "explanation": "Multiply: 15×10=150", "needs_review": false, "correct_answer": "150"}, {"id": 11, "type": "short_answer", "skill": "computation", "question": "Calculate: 17 × 20", "difficulty": "medium", "explanation": "Multiply: 17×20=340", "needs_review": false, "correct_answer": "340"}, {"id": 12, "type": "short_answer", "skill": "computation", "question": "Calculate: 14 × 20", "difficulty": "medium", "explanation": "Multiply: 14×20=280", "needs_review": false, "correct_answer": "280"}]