You should go to the department head. They can overturn it. Or go to the principal.

Just so you're aware, most teachers are idiots and they follow the curriculum book exactly. Any answer not in the book is wrong. Doing things a different way to get the same result is wrong. Basically you are there to learn how to do it THEIR way, not the correct way. In my opinion that's a horrible way to teach children because they won't end up thinking for themselves. I've been a victim of bad teaching myself, so I sympathize with your pain. School will not define your future.

thats the system. it doesn't matter if you are right, if the book says something else than you're wrong....

As George Carlin would say "Another type of people who ought to be hit in the head repeatedly with heavy machinery"

Wow! I heard this all throughout my years of education and heck the same mentality applied to my college professors. I recall once being creative and use Ben Ten as an example in one of my exams and my Teacher in college escalated that exam to the Head of Dept that I was trying to mock him by mentioning a cartoon in an Operating Systems exam. The world should call "education" as "institutionalization" coz that is what it is in the end

If the test is important take it to the dean of your school. I have done that before for a question on my final and was awarded the points back. However, be SURE that you are correct, and I mean 100% sure.

"The internet isn't a reliable source!"

My teacher always points out when a book is wrong. Maybe go to the principal?

Well if you were paying attention in class or you actually studied your textbook your teacher could have explained that to you before you wrote the test. Your teacher probably doesn't have a choice what he/she teaches.

The fact that you said you found a "government approved website" is an extremely clear sign that you're just a high-schooler that's pissed because you got a question wrong and you thought you were right. Teachers are there to help you, and if they are genuinely wrong about something, you should point out why, by citing your evidence. The teacher would apologize and correct their mistake in such a case, so either grow up, or make an effort.