From what I understood, the problem was two-fold  by Ziks511 -
1/28/13 4:44 AM  In Reply to: So what if she lip synced it by
Steven Haninger  It was cold and the band hadn't had sifficient
time to rehearse. I don't understand how they jumped from the
stated problems expressed by the band director to it being
Beyonce, who could probably have sung the anthem in her sleep,
even with the cold.  While the modern pop idiom isn't my
preferred listening material, Beyonce Knowles is a very talented
singer with a remarkable range, and the chops to do just about
anything.  The other element is that while she is a melismatic
singer (the overly ornamented style currently in vogue) she has
exceptional taste and precision in her use of them, and
consequently doesn't decend into the chasm of Maria Carey and so
many others who cover up defects in voice production and tone
with a lot of frippery.