[{"id": 1, "type": "short_answer", "skill": "subtraction", "question": "Calculate: 136 − 124", "difficulty": "medium", "explanation": "Subtract by place value, borrowing as needed.", "needs_review": false, "correct_answer": "12"}, {"id": 2, "type": "multiple_choice", "skill": "subtraction", "options": ["12", "10", "13", "260"], "question": "What is 136 − 124?", "difficulty": "easy", "explanation": "136-124=12", "needs_review": false, "correct_answer": "12"}, {"id": 3, "type": "short_answer", "skill": "computation", "question": "Calculate: 15 × 4", "difficulty": "medium", "explanation": "Multiply: 15×4=60", "needs_review": false, "correct_answer": "60"}, {"id": 4, "type": "short_answer", "skill": "computation", "question": "Calculate: 20 × 2", "difficulty": "medium", "explanation": "Multiply: 20×2=40", "needs_review": false, "correct_answer": "40"}, {"id": 5, "type": "short_answer", "skill": "computation", "question": "Calculate: 4 × 11", "difficulty": "medium", "explanation": "Multiply: 4×11=44", "needs_review": false, "correct_answer": "44"}]