Podkayne is a good book. I like Heinlein, but I find him unreadable at times, and inappropriate for kids in others. See, Lazarus Long, and “Time enough for love.”
Glory Road is an excellent book that she will probably love.
Very much agreed about Heinlein, That’s why I only suggested Podkayne. All his early books are highly readable and unobjectionable. The Rolling Stones is great, and you’ll find out who thought up Tribbles.
Another good early SciFi book is Little Fuzzy, if you can find a copy. I read it aloud to my kids and they loved it!