Here's why:
* Common nouns: Refer to general things, not specific ones. They are not capitalized.
* "Skip" as a noun: Can refer to the act of skipping, like "The children's skip was full of joy." It's not a specific person, place, or thing, making it a common noun.
However, "skip" can also be a verb (to hop lightly), an adjective (meaning missing or omitted), or even a noun referring to a specific item like a "skip bin" (a large container for waste).
So, whether "skip" is a common noun depends on how it's used in the sentence.