S.H.
Accidents happen.
It is childhood.
Even if they are older and potty trained.
Do not punish or scold. That will not help.
Kids HAVE accidents.
She is probably embarrassed, so she will not ask for a new underwear.
My daughter had accidents. In Preschool. In Kindergarten. In 1st grade.
ALL of her Teachers, Preschool, Kindergarten, 1st Grade... ALL said, this happens and is normal. Not abnormal. Other kids have accidents too. Not only my daughter.
The Teachers, do not make a big deal of it. They merely notice the accident, comfort the child, and have them change clothing/underwear. Discreetly. They do not draw attention to it.
Thus, for each grade my daughter was in, I always and per the Teacher, had extra clothes for her at school.
EVEN the Health Room lady, has TONS of extra underwear... for the Elementary school kids, in case they have accidents. Because, it DOES and will, happen.
A Teacher, SHOULD notice. And then change the child.
This is normal.
Your daughter is simply too embarrassed to admit and then ask for a change of underwear. Or she is embarrassed to ask to go to the Bathroom.
CAN the kids go to the bathroom, at ANY time? Or does her school only have certain times, the kids can go??? This also happens at some schools.
All the best,
Susan