Two students, Janelle and Corey, are ready to test their designs. Janelle made her solar oven by lining a piece of poster board with aluminum foil, shaping it into a cone, and placing it over a piece of black paper in an empty box. The food will go in a plastic sandwich bag on top of the black paper in the center of the cone. The image shows Janelle's cone oven.

cone shaped solar oven
Corey made his solar oven by lining the inside of a shoe box with black paper, placing a piece of plastic wrap over the bottom of the shoe box, and lining the lid of the box with aluminum foil. He used a pencil to prop the lid open at an angle. The food will go on the black paper under the plastic wrap. The image shows Corey's shoe box oven.

shoe box solar oven
Janelle's and Corey's designs both use aluminum foil, black paper, and either a plastic bag or plastic wrap. What is the purpose of each of these materials in the designs?