Many people are using Google Classroom with their students and co-teachers, but many are asking for an option to print all student assignments at once while in Google Classroom.
Currently, there is not a way to do this in Google Classroom. However, there are many workarounds for this.
First, you can install the app PDF Mergy, from the Chrome Web store into your Google profile. This app will allow you to drag and drop files from your device or from your Google Drive and it will merge all of your files into one file. Then you can simply print the file.
In addition, PDF Mergy will allow you to save your merged file to your local device or to your Google Drive. You can also give it a more descriptive name.
I created a short screen cast Enjoy!