Kami is a great tool for annotating on PDF's. It integrates beautifully with Google Classroom too! We have temporary free access through this year
Screencasting Tools Explained (Nate Breeden)
Kami for Remote Learning
Home Learning with Kami and Google Classroom
Using the Signature Tool
How to Use the Annotation Summary
Getting Started with Kami and Google Classroom Webinar
Kami for English
Kami for Math
Kami for Science
Kami for Special Education
MSD Kami Webinar-Host: Cody Glaze