In this new video I demonstrate how to use the Google Classroom mobile apps to create PDFs from scratch. As I demonstrate in the video, you can use the app to draw on a PDF or type on a PDF. The drawing option could be a great one for students to use in a mathematics class as they can easily sketch to show their work on solving a math problem.
On a related note you may be interested in How to Create Virtual Math Manipulatives in Google Classroom and How to Add Audio to Google Forms, Docs, Classroom, Slides, and Gmail.