The infinitive phrase is "to spend the afternoon tobogganing".
An infinitive phrase expresses the action in a sentence. They can often function as nouns, adjectives or adverbs. E.g.: To win the approval of her mother-in-law by cooking dinner was Mary's only hope. The infinitive phrase in bold functions as a noun because is the subject of the sentence. When the phrase explains 'how' it functions as and adjective, when the phrase explains 'why' it functions as an adverb.
The main theme of Edward Hirsch’s poem “Fast Break” is<u> the importance of teamwork</u>. Hirsch relates this theme to the reader through a colorful description of a fast break play in a basketball game.
