ur sooo sooo lucky my smaller sisters are not allowed to cover their hair at school because the school says there is a no hat policy so they can not break that rule even for them so they have gotten permission to wear a shawl to cover their other parts we live in a very small town 600 people and we are the only muslim family here.........we even had to fight the school over not giving another type of food when they are serving pork for lunch or breakfast.........also had to battle the lunch assistant over them telling the girls and my brother that bacon bits are ok to eat cuz they are not real bacon......one day my mom got a call from the school that her children were refusing to eat lunch at the middle school and the grade school and only sitting their while everyone was eating so she went to the schools to see what the problem was and told them well ur trying to feed them pizza with sausage they can not eat it and would rather go with out food than put something in their body that is forbidden..........now they offer a second selection to my smaller sisters and brother when they will be serving pork.......... 
Our school has a no hat rule as well but the constitution of the USA that forbids any establishment from infringing on the religious rights of its citizens tops any school rule
QUOTE
"Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof; or abridging the freedom of speech, or of the press; or the right of the people peaceably to assemble, and to petition the government for a redress of grievances."
It really depends on how old the girls are whether I would want to make a big deal out of it. If they're in grade school / elementary, I personally wouldn't make a big deal out of it because they aren't really required to wear it before puberty but if her school has an issue with it in the future then I'd take it to the school board.
I take my kids out of school early every Friday as well because of the Jumua'ah and I had to send a note explaining and talk to someone from the school board about that and they didn't give me a problem after I explained that I'll worry about their opinions on Friday when they start making the Jewish and Christian children come to school on Saturdays and Sundays
They also offered to to give the children private time together to pray during the day and excuse them from any activities that I notified them as being forbidden in our religion. Neither one of my kids has to take music class or dance (if there's music) or anything like that and in art class they are never required to draw, paint or sculpt the image of a living creature. My son also was exempted from sex ed this year and we did a health unit on our own to replace the grade. I can't afford private school so I've had to learn how to manuever the system
They also offer vegetarian lunches daily at all the schools in the area but my kids take lunch from home.
Of course, we moved from the country to the city last year and there are a lot of muslims in this area so they're pretty used to it.
