[{"id": 1, "type": "short_answer", "skill": "computation", "question": "Calculate: 20 + 70", "difficulty": "medium", "explanation": "Add systematically.", "needs_review": false, "correct_answer": "90"}, {"id": 2, "type": "multiple_choice", "skill": "properties", "options": ["Associative property", "Commutative property", "Identity 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: 6 × 6", "difficulty": "medium", "explanation": "Multiply: 6×6=36", "needs_review": false, "correct_answer": "36"}, {"id": 4, "type": "short_answer", "skill": "computation", "question": "Calculate: 18 × 18", "difficulty": "medium", "explanation": "Multiply: 18×18=324", "needs_review": false, "correct_answer": "324"}, {"id": 5, "type": "short_answer", "skill": "computation", "question": "Calculate: 12 × 3", "difficulty": "medium", "explanation": "Multiply: 12×3=36", "needs_review": false, "correct_answer": "36"}, {"id": 6, "type": "short_answer", "skill": "computation", "question": "Calculate: 5 × 7", "difficulty": "medium", "explanation": "Multiply: 5×7=35", "needs_review": false, "correct_answer": "35"}, {"id": 7, "type": "short_answer", "skill": "computation", "question": "Calculate: 10 × 18", "difficulty": "medium", "explanation": "Multiply: 10×18=180", "needs_review": false, "correct_answer": "180"}, {"id": 8, "type": "short_answer", "skill": "computation", "question": "Calculate: 6 × 3", "difficulty": "medium", "explanation": "Multiply: 6×3=18", "needs_review": false, "correct_answer": "18"}, {"id": 9, "type": "short_answer", "skill": "computation", "question": "Calculate: 14 × 9", "difficulty": "medium", "explanation": "Multiply: 14×9=126", "needs_review": false, "correct_answer": "126"}, {"id": 10, "type": "short_answer", "skill": "computation", "question": "Calculate: 12 × 20", "difficulty": "medium", "explanation": "Multiply: 12×20=240", "needs_review": false, "correct_answer": "240"}, {"id": 11, "type": "short_answer", "skill": "computation", "question": "Calculate: 9 × 11", "difficulty": "medium", "explanation": "Multiply: 9×11=99", "needs_review": false, "correct_answer": "99"}, {"id": 12, "type": "short_answer", "skill": "computation", "question": "Calculate: 8 × 4", "difficulty": "medium", "explanation": "Multiply: 8×4=32", "needs_review": false, "correct_answer": "32"}]