Everything you need to understand or teach The Keeper of the Isis Light by Monica Hughes.
Olwen Pendennis and her Guardian live in splendid isolation on the planet Isis of the star Ra, maintaining the beacon which announces the presence of this habitable planet to any space travelers, till the day of Olwen's tenth birthday. She would be sixteen in earth years, and she has never seen anyone but Guardian.
But eighty settlers arrive in the space ship Pegasus Two, with Captain Jonas Tryon. They will now live on...