These words "<em>are, is, am, is</em>" are known as direct or main verbs of a sentence. Thus they act as the doing words or the main action words in the sentences. Without them the sentences may be meaningless or incomplete.
In 1 above, <u><em>are</em></u> functions as a <em>Linking Verb</em>. The phrase a good student is a state of being and provides additional information (in third person singular) about the subject "You".
The same explanation goes for <u><em>is</em></u> and <u><em>am</em></u>.
Please note: Any word which in a sentence, that is used to connect a subject to an additional information about the subject is called a <u>Linking Verb</u>.
Fairfield is a town, so it would be very weird for a community pool to be bigger than it: all the other comparisons actually make a point, as the things compared are more similar