about -> content at coutses.new view, title -> name at notices.new view.
apply strong-parameter-wayto notices controller.
apply strong-parameter-wayto notices controller.
apply strong-parameter-wayto notices controller.
add dynamic contents to notice.index view
when create notice, we should add professor_id.
add dynamic content to notices.show view.
add index button to notices.show view.
add go to course button to notices.index view.
title -> name at courses.show view.
modify form_for path([@course, @subject]) in subjects.new view.
fixed fields_for problem in problem.new view.
modify assignments.new view for new nested resources(problem.assignments)
add 'back to course' button in assignments.show view.
fixed current_subjects and outdate_subejcts in course.show view.