She was reading "Ender's Game". Ender's Game is a 1985 military science fiction novel by American author Orson Scott Card. Set at an unspecified date in Earth's future, the novel presents an imperiled humankind after two conflicts with the Formics, an insectoid alien species they dub the "buggers". In preparation for an anticipated third invasion, children, including the novel's protagonist, Andrew "Ender" Wiggin, are trained from a very young age by putting them through increasingly difficult games, including some in zero gravity, where Ender's tactical genius is revealed. https://en.wikipedia.org/wiki/Ender%27s_Game