Your daughter is 11?
She can use this experience to strengthen her resolve.... and to just see it as an opportunity... to better herself and not compare herself to the others.
She can also try and talk with the Teacher... and discuss it & show maturity. But well, these things happens.
Maybe the others have been dancing longer than she has?
Has she attended all the rehearsals and lessons?
How is her attitude and "professionalism"?
She was in 2-3 dances, while the others were in 4.
Maybe her Teacher thinks she needs more performances under her belt...
It could be anything. You/she can always ask the Teacher, right?
My daughter takes Karate. She is 7. She is a 'white belt.' She has progressed very well. She has seen others in her rank, get another new 'belt color' before she did....and was in class with "Newbies" too. BUT, She does not take it personally... but tries her best, always and is very determined. The others that got another belt color ranking before she did, was not always 'better' than her... but had been taking Karate longer than she has... to a certain extent, the Teachers promote the kids to a higher belt color according to how long they have been in Karate and on the child's personal improvement and understanding of the movement forms... they do not promote a child just according whim or favoritism. For my daughter, she had to work on a particular movement... which she has. Just ONE certain aspect of her "kata" movements. Whereas the others that got promoted, did do that movement accurately. My daughter, used that "disappointment" to improve her resolve... and she plugged through it... knowing, that she was only getting better... and would be better in time.
She is now, going to be promoted to another belt color, today! She is PROUD. She stuck it out... even if her classmates went ahead of her in rank. She didn't let it 'hurt' her or make her give up. She KNOWS now, that she IS deserving of it. AND... her Teachers have given her accolades... and really 'respect' her resolve and the way she handled it. WHICH is what they look for... the 'character' of the child in how they approach their talent... and using it to make strides. Her Teachers, have given her compliments... on her ability, now... and she earned it. She knows that. She is very proud... for her, it is not about being in the same level as her friends/classmates... but on how SHE progresses, personally. That is what matters to her. And her Teachers take note of that.
Your daughter, is going to have to deal with it. It is all a part of 'becoming' better... and having dedication, to their chosen talent and endeavor.
all the best,
Susan