Some people may say that if students' materials are not uniform, it will be more troublesome for teachers to comment in class. In fact, this problem is very easy to solve. Let students write exercises to consolidate knowledge points and master knowledge points, not just brush questions. Teachers should make unified questions, and they can find questions for the whole class to do. If students have questions when reading the supplementary books they bought, they can ask the teacher for help. I believe that teachers are also happy to help students. It will be very happy to see students studying hard and being teachers.
In addition to completing the homework assigned by the teacher, students can also buy different textbooks according to their own needs, because some textbooks focus on the basics, while others are suitable for people with strong ability to expand and improve.
I think the Ministry of Education will strictly require schools to do so. Of course, the Ministry of Education also has other considerations. Maybe the school will set up its own service fee and handling fee to get the difference. Of course, these do not need students to consider.
Although the materials that teachers ask students to buy must be carefully selected, it is no problem to buy the materials recommended by teachers, but we should consider the students' own needs. Students can ask their teachers for advice. As long as the child is willing, how can parents not buy it for him?
Of course, there are many supplementary books on the market now, which is very troublesome to choose. However, as long as it is published by a well-known publishing house, it is generally worth buying. If students write and publish by themselves, it is actually not as good as those formal ones. This is my experience and lesson, for reference only. If you don't consider the price, you can buy more.
Finally, I nagged a few words. There is really nothing black and white in the world, just as students can't be said to be certain in essence if they don't buy specified materials. It's all about how much, depending on how you look at it.