As an American, I do find it offensive that she would represent a publicly funded school with a prayer that did *not* represent that school.
If I was still Christian, I would be concerned about the fact that she openly lied to God, while praying.
"This *will* be a day of death to old habits, thought and ideas. This *will* be a day of new life." Well, maybe she wants it to be that for herself, but she's speaking for everybody, and I'm sure not everybody has that intention.
"We praise you, God. We worship and adore you. We stand in awe of the king of the universe..."
Now that part is an outright lie. It is not a religious school, not everybody there is Christian. Many are probably atheist or non-religious. To claim otherwise is a lie. To claim otherwise *to God* is a very silly lie. Surely, if the Christian god exists, he/she would know who praises him and who doesn't. Surely, when this girl bows her head in prayer and claims to speak on behalf of a group that praises him, when she had to fight to be allowed to pray *at all,* he/she would know that she is lying. As a group, they are not praising him. Individually, some are, some aren't.
"Thank you Jesus for your [death?]. We do not esteem it lightly." Some there do. Some don't believe it happened at all, and some don't care. It is also completely irrelevant to the reason they are gathering so, as a group, they aren't esteeming it much at all, positively or negatively.
"You are holy, and *you alone* will be lifted up in this place, and in all of our lives." Lie. Outright, brazen lie. It's a school of education, not religion. "Lifting up" God there, as a school, is legally inappropriate, and probably doesn't happen very often. Lifting up "only" the Christian god...huh? Well, she is calling love of knowledge an idol, and thus a competitor for god's affections, so clearly other 'gods' *are* being worshiped there--this love of knowledge and education. And it will continue to be praised, because that's the entire point of the establishment: it's a secular school, where the teaching of religion is *illegal.*
She was speaking on behalf of the school--a school which didn't really *want* her to pray on their behalf at all, as evidenced by the fact that there was controversy over it, and they had to settle on one that was "short and nonoffensive." If they had wanted her prayer, there would have been no controversy, and no such compromise would have been necessary.
As a representative of these people, she gave an unwanted prayer, in which she made untrue claims about the nature and beliefs of those people, repented for things that, likely, many of them did not view as sins, and made promises to God about how the school would run that are completely at odds with the very nature of the school.
As an American, I'd say what she did is sort of irritating. But from a Christian point of view, it's pretty horrific.