Audition song - Mary Lennox in Secret Garden?

"I Know Things Now" from Into The Woods is a good child's song, and of course anything from Annie (plus Annie has the nice orphan parallel). "Where is Love?" from Oliver! is a good child's song as well and can just as easily be sung by a girl. "Do-Re-Mi" from The Sound of Music and "Goodnight My Someone" from The Music Man are also good choices, and would be in the appropriate age range.