Daughter Losing Her Hair

How big is huge? A centimeter? An inch or bigger?
And where - on the top or side or back of her head?
Does she wear her hair in a tight pony tail or in tight braids all the time?
Pulling hair and keeping it under tension can cause hair loss.
It's sometimes called ballerina baldness.

It might be ringworm (a fungus) and if it is an anti fungal cream (like tinactin) will clear it up.
Does she use anything to curl or straighten her hair - curling iron, etc (did she burn her scalp?)?
How is her nutrition? Too much vitamin A or not enough Biotin can affect hair growth (and nails too).

http://children.webmd.com/guide/hair-loss-in-children

This happened to me. It was alopecia caused by stress, sometimes it is autoimmune and sometimes no one knows why it happens. Take her to the dermatologist to confirm.
If alopecia, they treat the area with steroid shots around the perimeter of the spot about every four weeks until your doc sees improvement . My hair grew right back after two treatments and we did one more for good measure. This was about a year ago and I have had no issues.
sometimes it is a one-time thing. It was NOT costly even though my insurance did not cover the treatments, it was still discounted because I had insurance.

No, it's not normal! Talk to a doctor! Usually this is a stress problem, but sometimes it is a skin disorder. Either way, you don't want this to continue.

Alopecia. No, it's not normal, and you need to get her to a doctor. It's usually an autoimmune disorder, and often steroid or cortisone shots to the affected area are the treatment. You want to nip this in the B., so get her to the doctor ASAP.

Make sure she hasn't been pulling out the hair in that spot (trichotillomania).

You should have her thyroid checked by your family doctor. This is certainly not normal.