I think teachers make students switch their essay and grade others is an action didn't respect private secret. As age, idea, and character, scores should also be personal things that should be respected and have personal power to decide whether he or she wants to let others know or not. But sometimes teachers didn't care or realize this behavior might make students uncomfortable. For example, if some students cannot write a good essay or have some strange idea to write, and other students know, they might laugh at those students who have strange idea. That would really hurt their feelings. They might not work hard next time or not like this class any more. This is why I said they should be respected and protected as private secret.
哪有这么高档的app
grammarly https://app.grammarly.com/ 这个是网页版链接
批改网~
我们大学就用的这个