The given sentence is in Indirect Speech. It expresses a universal truth: “The Earth revolves around the Sun.”
Rule: Universal truths and facts remain in the present tense, even when reported.
Therefore, the correct direct form remains:
\(\Rightarrow\) “The teacher said, ‘The Earth revolves around the Sun.’”
\boxed{\text{Correct Direct Speech: The teacher said, “The Earth revolves around the Sun.”}}