Because they don’t have the same final use,
And they don’t have the same content and chapters.
For notes table for student, I think it’s more aesthetic for student as they only write for themselves. And form for teacher, because they have different students, so they can write the name of the person and click on.
And they don’t communicate together, it’s completely private.
My original thinking is that the records for users can be in 1 table, then notes can be in 1 table. Say a teacher has 10 students, then he can have 10 notes for those students for each chapter, but if you have a better design for your use case then it’s great.