It could be….
the charger isn’t plugged in or getting power
Check that your charger is plugged snuggly into the Chromebook’s charger port (for devices in grades 5-8, try the usb-c charger ports on either side). Make sure your charger (the brick shaped piece) is plugged tightly into the AC cord. Check that the outlet you are plugged into is not switched (some outlets may have one outlet that is controlled by a light switch and another that is always on).
the Chromebook is frozen
Try performing a hard reset on the Chromebook by pressing Refresh + tapping Power until the computer returns to a login screen. This may take at least 15 times.
the charger or Chromebook charging port is damaged
If you happen to have another sibling with a working Chromebook charger that matches yours, give it a try. If that works, your charger has most likely failed. If it does not work you may have a faulty charging port on the Chromebook. In either case, contact your building main office and arrange for a device swap.