When you don't have Internet...
Things to do offline - https://support.google.com/chromebook/answer/3214688?hl=en
Remind students that even if they don’t have Wi-Fi access away from school, there’s a lot that they can do with their Chromebooks:
Read and respond to emails. The emails are sent as soon as students get back online.
Take, view and edit photos and videos.
Take notes in the Google Keep app.
Work on Google Docs, Sheets, and Drive files.