All DS does for schoolwork at home is homework, never extra study even for mini-tests. He's been doing fine so far so I was fairly relaxed about it. However, he brought back only history homework for this holiday and nothing else. So I am thinking to get some textbooks for self-study, maybe maths, biology, chemistry, and perhaps also English and German, aiming 30-60mins a day. I think something lighter and shorter than full-on GCSE textbooks would be better for him since he doesn't have a habit to study during a holiday? Any recommendation would be greatly appreciated!