Have students read the book and watch the film. I suppose you could have them watch both films instead, too, if you wanted. Then you need your students to compare and contrast the following topics:
1. Wall-E vs. Doon/Lina (character to character compare/contrast)
2. The Axiom Spaceship vs. The City of Ember (setting to setting compare/contrast)
3. The CEO of Buy n' Large vs. The Builders (character to character compare/contrast)
4. Earth vs. Earth (setting vs. setting; in other words, what does Earth look like in both stories?)
5. Scriptwriter's message vs. Author's message (compare/contrast author's purpose)
When I taught this, I had my students create a Venn Diagram for each compare and contrast topic. Then I had them choose one compare contrast topic to make into a paragraph-long response. You can alter this to meet the needs of your students; you might have them do a chart or diagram for each one, or one overall for each story. You might have them write about a variety of compare and contrast topics, or only choose a few. You might have them turn it into a compare contrast essay also. The possibilities are many, depending on what you want to do with it.