This resource appears to be designed to build towards this disciplinary core idea, though the resource developer has not explicitly stated so.
Comments about Including the Disciplinary Core Idea
The authors are fairly open-ended in their suggestions for student testing of their respective designs--consider having the class agree on a series of uniform tests that each of the solar cooker designs will be put through in order to make direct comparisons between designs (e.g, measuring the change in temperature of 250 ml of water for 45 minutes; of air in a closed container; of a hot dog), and have them use these to determine the relative efficiency of each of the designs.