Google announced that you can now use Google Slides (Presentations) offline too. While using Google Slides offline you can create new slideshows, edit slideshows, comment on slideshows, and present your slides.
In you already have offline access to Google Documents enabled, you don't need to do anything to make Google Slides work offline. That will happen for you automatically. If you do not have offline access to Google Documents enabled, click here for directions on how to enable it.
Applications for Education
Google Slides offline is a great addition to Google Docs offline. If your students are using Chromebooks or just a Chrome browser, but they don't have Internet access they can still work on their presentations and documents for their classes.