Curated OER
Why Don't Whales Have Legs?
High schoolers are given a variety of materials and are asked to design a heat loss experiment that results in a reasonable explanation of "Why don't whales have legs?" students work with the theory of natural selection.
Indiana University
Ensi: Blocks and Screws Lesson Plan
The Evolution and the Nature of Science Institute offers lesson plans that investigate the vestigial organs in such a way as to better explain their imperfections as proof of evolution rather than the result of "intelligent design."