What theme is expressed in the statement: “They have a word for people our age. They call us children and treat us like mice”?

Children are manipulated in this story. For Ender, isolation is used in order to achieve what the adult leaders want. Throughout the novel, Graff and Mazer isolate Ender from all of the other students at Battle School and Command School. Graff explains his reasoning multiple times; in his isolation, Ender will grow strong enough to beat the buggers. Graff thinks that Ender cannot expect anyone to help him at any time, or else he will not develop the willpower and strength to win at critcal points. Thus, Graff believes that the isolation teaches Ender to be strong. Ender reflects this idea in his treatment of Bean when Dragon Army is first created. Also, while Graff, Mazer, and Ender all hate the fact that they have to isolate their protégés, they continue on the path of isolation in order to develop them.