[{"id": 1, "type": "short_answer", "skill": "addition", "question": "Calculate: 126 + 120", "difficulty": "medium", "explanation": "Add by place value, regrouping as needed.", "needs_review": false, "correct_answer": "246"}, {"id": 2, "type": "multiple_choice", "skill": "addition", "options": ["256", "251", "246", "245"], "question": "What is the sum of 126 and 120?", "difficulty": "easy", "explanation": "126+120=246", "needs_review": false, "correct_answer": "246"}, {"id": 3, "type": "true_false", "skill": "properties", "question": "The commutative property means 126+120 = 120+126.", "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: 9 × 12", "difficulty": "medium", "explanation": "Multiply: 9×12=108", "needs_review": false, "correct_answer": "108"}, {"id": 5, "type": "short_answer", "skill": "computation", "question": "Calculate: 8 × 15", "difficulty": "medium", "explanation": "Multiply: 8×15=120", "needs_review": false, "correct_answer": "120"}]