Yes. You can use offline-ready apps to keep using a Chromebook when it’s not connected to the Internet. Below are some examples:

• Read and write emails with Offline Gmail
• Write a note or make a list with Google Keep
• Create and edit documents, slides or spreadsheets with Google Drive apps (Google Docs, Sheets and Slides)
• View and RSVP to events with Google Calendar
• View and edit photos saved with the built-in photo editor
• Enjoy music or movies with the built-in media player