The intent is to extract money from vulnerable young people, which is why they change the problem sets every year without changing the educational content.
That is the intent of the publishers when they change frequently. If the teacher/professor gets a cut then they might share the same incentive to update regularly.
But at the core from a teaching perspective, the general reason for assigning books that might only have a portion used in class is because the teacher thinks the book as a whole will be helpful in understanding the content. Otherwise they would just recreate their own version of that chunk of information if they aren’t getting a cut from sales.
The intent is to extract money from vulnerable young people, which is why they change the problem sets every year without changing the educational content.
That is the intent of the publishers when they change frequently. If the teacher/professor gets a cut then they might share the same incentive to update regularly.
But at the core from a teaching perspective, the general reason for assigning books that might only have a portion used in class is because the teacher thinks the book as a whole will be helpful in understanding the content. Otherwise they would just recreate their own version of that chunk of information if they aren’t getting a cut from sales.