1. At the first class, we have fine arts.

2. In the first class, we have fine arts.

Which preposition do we ahve to use?

1. At the first class, we have fine arts.

2. In the first class, we have fine arts.

Which preposition do we have to use?

Use "in" -- better yet, use "during."

To determine which preposition to use in this context, we need to consider the specific context and meaning of the sentence.

In sentence 1, "at the first class, we have fine arts," the preposition "at" is used to indicate a specific location or point in time. It suggests that "we" (presumably students) have fine arts as part of the curriculum or schedule during the first class.

In sentence 2, "in the first class, we have fine arts," the preposition "in" is used to indicate a location within a space or an abstract concept such as a time period or category. It suggests that fine arts is one of the subjects taught or included within the first class.

Both prepositions can be used, but the choice between "at" and "in" depends on the intended meaning. If you are referring to fine arts being part of the curriculum specifically during the first class, you would use "at". If you are referring to fine arts being one of the subjects taught overall within the first class, you would use "in".