What is a good song to sing for a school talent show?

I'm still high school and in the finals of the school's talent show. I sang Celine Dion's 'My Heart Will Go On' at the semi finals and now I have to sing a strong song with a meaning behind the words (lyrics).

I was thinking of doing Kate Winslet's 'What If'. I sang that at my Christmas prom in the seventh grade.

If you have a good song you think is for me, write it in your comment and I'll download it onto my iPhone 5 and listen and try and sing along with it.

Rack City
By: Tyga

I would suggest something different for you.
take a flashback there was a song by bob Dylan "knock knock on heaven's door" which was performed by Avril in different and amazing style.
so i would propose you "wake me up when september ends", "21 guns"
in your own style of throwing vocals.
you could also experiment soundtracks like "only time" in sweet november.
"hello" is also a good number by solveig.
"you are still the one" by shania twain, "whenever"-shakira.

and if you wanna really surprise the school you can pick up hip hop if you have good hold of this genre.