What job is the noun clause doing in this sentence? a polite guest will eat whatever is served.

The noun clause 'whatever is served' is functioning as  a direct object. You can check this by replacing the noun clause with the word 'something'. That is one way to check that a part of the sentence is a direct object. Also, if you check the meaning of the verb "eat" in a dictionary, you will notice it usually needs an object to complete its meaning.

what are the sentences?

to me i think class room sitting education is better. i do online school and i have not learned a think haha. when i sit in the classroom i just sit there and kind of pay attention but still i get so far ahead in the class when im doing online i have nothing else better to do but play video games and i sit in school and learn and have friends and just actually learn. when i'm doing online i sit here listing to music and get on and and look up the answers i guess that is my fault for being a cheater. but to be honest i think sitting in the classroom is better.