Edit Material Button

What is this new button in my Google Classroom? This shows up when I preview any PDF as a material on a Chromebook with the latest Chrome OS and the Kami extension and app already installed. Any help would be greatly appreciated!

Hi there,
This is a new feature that we are currently testing in Google Classroom. It is only in beta mode and is available to users who have requested to try new Kami features during the beta stages. This new feature allows you to edit material and push out live changes to an assignment after being sent to students. Let us know if you have any feedback about this new feature! - Kayla from Kami

@Kayla Thank you.