Here's why:
* Nouns are words that name people, places, things, or ideas (e.g., dog, city, book, freedom).
* Verbs are words that describe actions or states of being (e.g., run, sleep, think, be).
* Prepositions are words that show the relationship between a noun or pronoun and another word in the sentence (e.g., on, in, under, beside).
Contractions are shortened forms of words where a letter or letters are omitted, usually with an apostrophe taking their place (e.g., can't, don't, I'm). Contractions are not a part of speech themselves, but rather a way to combine words.