[{"id": 1, "type": "short_answer", "skill": "computation", "question": "Calculate: 38 + 21", "difficulty": "medium", "explanation": "Add systematically.", "needs_review": false, "correct_answer": "59"}, {"id": 2, "type": "multiple_choice", "skill": "properties", "options": ["Commutative property", "Associative 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: 15 × 18", "difficulty": "medium", "explanation": "Multiply: 15×18=270", "needs_review": false, "correct_answer": "270"}, {"id": 4, "type": "short_answer", "skill": "computation", "question": "Calculate: 7 × 4", "difficulty": "medium", "explanation": "Multiply: 7×4=28", "needs_review": false, "correct_answer": "28"}, {"id": 5, "type": "short_answer", "skill": "computation", "question": "Calculate: 6 × 6", "difficulty": "medium", "explanation": "Multiply: 6×6=36", "needs_review": false, "correct_answer": "36"}, {"id": 6, "type": "short_answer", "skill": "computation", "question": "Calculate: 10 × 8", "difficulty": "medium", "explanation": "Multiply: 10×8=80", "needs_review": false, "correct_answer": "80"}, {"id": 7, "type": "short_answer", "skill": "computation", "question": "Calculate: 20 × 11", "difficulty": "medium", "explanation": "Multiply: 20×11=220", "needs_review": false, "correct_answer": "220"}, {"id": 8, "type": "short_answer", "skill": "computation", "question": "Calculate: 8 × 15", "difficulty": "medium", "explanation": "Multiply: 8×15=120", "needs_review": false, "correct_answer": "120"}, {"id": 9, "type": "short_answer", "skill": "computation", "question": "Calculate: 4 × 4", "difficulty": "medium", "explanation": "Multiply: 4×4=16", "needs_review": false, "correct_answer": "16"}, {"id": 10, "type": "short_answer", "skill": "computation", "question": "Calculate: 3 × 19", "difficulty": "medium", "explanation": "Multiply: 3×19=57", "needs_review": false, "correct_answer": "57"}, {"id": 11, "type": "short_answer", "skill": "computation", "question": "Calculate: 17 × 11", "difficulty": "medium", "explanation": "Multiply: 17×11=187", "needs_review": false, "correct_answer": "187"}, {"id": 12, "type": "short_answer", "skill": "computation", "question": "Calculate: 14 × 20", "difficulty": "medium", "explanation": "Multiply: 14×20=280", "needs_review": false, "correct_answer": "280"}]