In a small school we use WP to create class-blog posts, therefore each posts may be assigned to a class-blog category representing the class (Year 1, Year 2, etc). While this was fine until school end, for next year it won't make much sense as students are moving to next-year "classes".
- Delete all last-year class-blog posts
- Rename old categories to something else such as "2017.18 - Year 1" and create new categories for next year
- Leave as is
Solution number 2 seems good, but this will make grow the categories list over time and may lead to confusion for teachers creating posts (having to scroll through longer lists of categories)