I saw these super-cute colossal burgers on Artolazzi's blog, and I just HAD to do them with my fifth graders! This spurred a whole class discussion (for the duration of our project, which was 2.5 classes) about the food challenges on Man v. Food. It was so much fun! 
Each student got a sheet of black that was 24x12. They started with the "placemat" and then the bun. For the bun, they ripped some corrugated cardboard to expose the bumps and filled up their burger from there! 
I love the different textures and elements the kids managed to fit into the burger. This was a great lesson to teach the kids how to fill and entire composition, too! 