Dictionaries are alphabetized. We're looking for words that are alphabetically after "crochet" but before "crossbones". "Criticize" starts with cri-, which comes before cro- and is therefore outside of the range. "Crocodile" begins croco-, which is after croch-, and before cross-. The same for "croquet" and "crocus". "Crouch" begins crou-, which comes after cros- and is therefore out of range. "Crocodile", "croquet", and "crocus" would be on that page.
The function of the Introduction is to serve as a 'map' of the essay, outlining to your reader the main argument and points which you develop in your essay.
