Here are two options for dealing with PDFs from students.

Commenting in Google Drive

While you can’t annotate PDFs in Google Drive, you can comment on them. A student or teacher can add comments to PDFs completely in Google Drive without using any other software.

Annotating PDFs in Xodo

Students and staff can also write on PDFs using XODO PDF Reader & Annotator ( PDFs can be opened from Google Drive or uploaded from the downloads.