- What are the advantages and disadvantages of an animal being large?
- Give an example of how animals adapt to their environments.
- What is the island rule, and how does it work?
- What happens to the typical size of snails in deep versus shallow water?
- Describe in your own words two possible explanations of why the island rule
might be true.
- Why does McClain consider the food-based theory unique and useful?
- How has McClain's research expanded the applicability of the island rule?
- What are McClain's plans to continue his research in the future?
- Why would variety in related species be evolutionarily logical and
practical? See www.pbs.org/wgbh/evolution/library/02/6/text_pop/l_026_01.html 
- Why do you think McClain choose to study sea snails and not some other group of species? See www.oceanexplorer.noaa.gov/explorations/05deepcorals/background/deep_sea_snails/sea_snails.html 
(National Oceanic and Atmospheric Administration).
- Describe the ways in which the deep sea is evolutionarily similar to an
island and how it is different.
- How do the illustrations in this article help you understand what the writer
means? What other illustrations might be helpful?
- Might there be animals that are the same size on the mainland and on an
island? Why would certain animals not vary in size?
On a map, locate an island where you can find pygmy elephants and another island where you can find giant rats. See en.wikipedia.org/wiki/Pygmy_Elephant  and en.wikipedia.org/wiki/Flores_Giant_Rat (Wikipedia).
- In the classic science fiction novel Twenty Thousand Leagues Under the
Sea, Jules Verne described a number of sea creatures that were an unusual
size. What do such descriptions add to the story? Why are giant animals
particularly interesting? See en.wikipedia.org/wiki/Twenty_Thousand_Leagues_Under_the_Sea 
- Jules Verne's novel The Mysterious Island is a sequel to Twenty
Thousand Leagues Under the Sea. What sorts of animals play roles in this
book? Why does the author introduce them? See en.wikipedia.org/wiki/Mysterious_Island  (Wikipedia).
A princess visits an island inhabited by two tribes. Members of one tribe always tell the truth, and members of the other tribe always lie. The princess comes to a fork in the road. She needs to know which road leads to the castle so as to avoid the fire-breathing dragon and rescue the prince from the wizard holding him captive in the castle. Standing at this fork in the road is a member of each tribe, but the princess can't tell which tribe each belongs to. What question should she ask to find the road to the castle?