If you are allowed to add extensions, these provide a more stable experience than random websites and often support gamepads.
You closed the tab without clicking "Export Save." Web emulators store saves in your browser cache. If you clear history or your school auto-wipes cache on logout, it’s gone. Always download the save file to your Drive. gba emulator school chromebook
Warning: This is high-risk. Most school IT departments can remotely detect if Developer Mode is enabled and may put the device in a "Wipe" loop or issue a disciplinary referral. If you are allowed to add extensions, these