"Well, we don't need mothers for that." He sees the sadness in her face. He understands--he's seen how kids act with their mothers, and obviously, the bond is supposed to be very strong. Aang's never felt an absence in his life, but he can see how it could be hard for someone else to imagine how he couldn't. "The older boys would sometimes sing to us when we were going to bed. The monks would teach us everything we knew. We all loved and took care of each other."