[{"id": 1, "type": "multiple_choice", "skill": "fractions", "options": ["1/2", "3/8", "3/4", "2/4"], "question": "What is 1/4 + 2/4?", "difficulty": "medium", "explanation": "Same denominator: add numerators. (1+2)/4=3/4.", "needs_review": false, "correct_answer": "3/4"}, {"id": 2, "type": "short_answer", "skill": "fractions", "question": "Simplify: 6/8", "difficulty": "medium", "explanation": "Divide numerator and denominator by GCF (2): 6÷2/8÷2=3/4.", "needs_review": false, "correct_answer": "3/4"}, {"id": 3, "type": "short_answer", "skill": "computation", "question": "Calculate: 20 × 4", "difficulty": "medium", "explanation": "Multiply: 20×4=80", "needs_review": false, "correct_answer": "80"}, {"id": 4, "type": "short_answer", "skill": "computation", "question": "Calculate: 6 × 9", "difficulty": "medium", "explanation": "Multiply: 6×9=54", "needs_review": false, "correct_answer": "54"}, {"id": 5, "type": "short_answer", "skill": "computation", "question": "Calculate: 7 × 4", "difficulty": "medium", "explanation": "Multiply: 7×4=28", "needs_review": false, "correct_answer": "28"}, {"id": 6, "type": "short_answer", "skill": "computation", "question": "Calculate: 18 × 7", "difficulty": "medium", "explanation": "Multiply: 18×7=126", "needs_review": false, "correct_answer": "126"}, {"id": 7, "type": "short_answer", "skill": "computation", "question": "Calculate: 11 × 15", "difficulty": "medium", "explanation": "Multiply: 11×15=165", "needs_review": false, "correct_answer": "165"}, {"id": 8, "type": "short_answer", "skill": "computation", "question": "Calculate: 16 × 13", "difficulty": "medium", "explanation": "Multiply: 16×13=208", "needs_review": false, "correct_answer": "208"}]