Final answer:
The situational irony in "The Storyteller" arises because Cyril does not accept his aunt's weak explanations about the sheep, and he is not distracted by cows despite her expectation.
Step-by-step explanation:
The instances of situational irony in the excerpt from "The Storyteller" occur when the boy, Cyril, continually questions his aunt's explanations about the sheep and the grass. Despite her attempts to invent satisfactory answers, Cyril does not accept the weak explanations provided by his aunt.
Moreover, the aunt expects Cyril's interest to be diverted by a distraction, the cows, which ironically, had been commonplace in the fields they passed.
Ironic expectations play a crucial role here as the aunt expects her explanations to be enough for Cyril, and she also anticipates Cyril to be distracted by the cows. However, the outcomes are quite different from her expectations, elevating the situational irony present in this interaction.