Movenote is a website, Chrome web app, Android, and iOS app that allows you to create narrated presentations.
The app supports Google authentication, so students don’t have to create accounts, and there is also an education version that removes the ads. It’s the easiest app I’ve found for allowing students (or teachers!) to record narrated slide shows to share.
Movenote can open your slides directly from Google Drive, and they don’t even need to be a Google Slides presentation. Adding a Google Doc to a Movenote shows each page of the doc when you click through the slides. For GMail, Movenote offers an extension that allows you to create a Movenote when composing an email. I could see this being used, for example, to explain a document that is being sent.
I’m very impressed with Movenote and what it can do, it’s fun to use!