Is Arnie studies rock and minerals with his class a action verb?

Yes, "studies" is an action verb in the sentence "Arnie studies rock and minerals with his class."

Here's why:

* Action Verb: An action verb describes an action that the subject of the sentence is doing.

* Subject: The subject of the sentence is "Arnie."

* Action: Arnie is performing the action of "studying."

Therefore, "studies" is an action verb because it describes the action that Arnie is performing.