The real problem may be in your educational system, whose operating hours may be incompatible with the standard, pre-set clock phase that most models naturally acquire at that age.
I suggest contacting your local school board to continue troubleshooting.
Now, disabling the wifi after 4pm or completely, that would be a different question.
What's even more crazy is that often when I attempt to silence the low battery warning by placing the Small Child in the charger, it often refuses to begin charging until the battery has been entirely depleted, so along with not being dismissable, even attempting to charge the Small Child does not stop the low battery warning consistently! I believe this is likely a bug, but I haven't yet been able to consistently replicate it to file a bug report despite experimenting with various charging and usage schedules.