In the book Wonder, Via used symbolism by saying the planets are falling out of alignment. By falling out of alignment, she means, that August was the sun and Via and her parents orbited the sun and that they are now paying attention to Via more. The symbol in this is that there are planets and asteroids (family and friends) and they are all paying attention to him.
In the book Wonder, August's dad used symbolism by saying "So sending him off to middle school is like a lamb to the slaughter". By a lamb to the slaughter, Auggie's dad means that Auggie doesn't really know what he's getting into. The symbol in this is that Auggie is the lamb in this situation so the lamb doesn't know whats going on.
In the book Wonder, Auggie cut off his Padawan braid. The symbolism in this event is that he is getting older and not really a little kid anymore.