The ISS is a great object for girls to spot in the night sky. It is fairly bright and easy to pick out from the stars because it is moving quite rapidly. But that rapid movement also means it is necessary to be ready for it as it will only take between 1 and 4 minutes to pass over head.
NASA has put together a website to help you determine exactly when the ISS will pass over your site. You can even set up a text message reminder (but I haven’t tried that).