Today our entire class (was, are) excited about the talent show.

Is was the correct answer for the sentence?

class is singular...was

classes is plural....are

Our class is excited
Our classes are excited.

The adverb "Today" indicates that it's happening now. To use "was" indicates past tense; to use "are" indicates present tense. What do you think?

You are dealing with a collective noun here, too -- "class" -- so read this:
http://grammar.ccc.commnet.edu/grammar/plurals.htm#collective_nouns

was

To determine the correct answer for the sentence, we need to identify the subject of the sentence and whether it is singular or plural.

In this case, the subject is "our entire class." "Class" is a collective noun, which can be singular or plural depending on the context. If you are referring to the class as a unified group, then it is treated as singular. If you are emphasizing the individual members of the class, then it can be treated as plural.

In the given sentence, it seems like the class as a whole is being referred to since it says "our entire class." Therefore, the correct answer would be "was."

However, if you think the individual members of the class are being emphasized, then "are" would be the correct answer.

So, depending on the intended meaning of the sentence, either "was" or "are" could be correct.