Germans should be taught about all German states after all it is your history and ancestory. German unification should be taught in school it's the reason "Germany" as nation exists. It will be neccessary to talk about Prussia as it was the main German state pushing for a greater Germany excluding Austria respectively.
I'm a bit of a history nerd, and yet, I also have learned very little about Prussia. If your taking a U.S. history class, than that's understandable. But I have taken advanced classes where we did discuss Prussia during the Napoleonic Wars and prior to WWI in the formation of the Austro-Hungarian Empire. Prussia was a very influential nation during its time, and was renowned for its military strength. That being said, history classes should not have a preference for Prussia. Usually, history lessons are taught in the order in which the current topic has relevance to the previous topic. So if you study Napoleon, you'll learn about Prussia. If your that interested, you could always search the internet for more information.