Clarifying だから use at the end of a sentence

Question

I was given this sentence:

ここが、きみの クラスだから。

The explanation I was given is that the から at the end is used when giving information. What is the だ used for? What are other examples of だから usage?

Answer 1

「から」 used to indicate a cause or reason must follow a verb or adjective. 「だ」 is the copula 「である」, which binds the noun it follows with the causative particle「で」 and the existence/possession verb 「ある」 in order to turn the noun into a verb clause.

Answer 2

A から B means 'B because A', and here, the B part is omitted, expecting the addressee to reconstruct it. See my answer to a related question.

だ is the copula, and is here because the because-clause ends with a noun. Depending on the type of the predicate, there are different endings.

君がクラスに来たから。 [verb]
ここは寒いから。 [i-adjective]
ここは静かだから。 [na-adjective]
ここが君のクラスだから。 [noun]