By default, Book Reviews completed by students are the only activities that display publicly on the Class Shelf. You can choose to also display Journal Activity Answers, in addition to Book Reviews, on the Class Shelf for all to see, including yourself as the teacher.
To display Answers on the Class shelf, click the drop-down in the top right of your teacher account and choose Settings. On that window, select Class Shelf.
There will be an option to display both Book Reviews and Answers: