Haddix brings forth the possible problem of overpopulation in a futuristic America, approaching the topic using historical references such as, "the one child law" in China and how a possible mini-Holocaust could result because of it. It also addresses how a totalitarian government might take advantage of a food shortage to create such a law "no more than two children" as we see in the book,forcing people to forfeit their reproductive rights, as the government begins sterilizing women after Luke is born. Or forcing parents to hide their children.
You did not specifiy the age of your students. If you are teaching high schoolers I reccommend Schindler's List. You could really drive the historical comparisons home. If you are teaching younger students I recommend City of Ember.