Requirements to teach.....

So I thought to myself recently, "I know what I want to go into career wise....but what kind of classes will I need to take to get said degrees and endorsements to teach?" well, I decided to do a little research and.... I'm not quite sure what to think.

I want to do a double major in college-- US history and German. Simple enough, right? For an endorsement to teach German, I need to obviously pass German. Apparently, according to this PDF file I found (it was created by the State of Iowa), the endorsement I need is
126 5‐12 German, whatever that means.

As for US History, I thought it would be cool to possibly teach an AP level class as well as a regular level.... meaning, I would need to be endorsed to teach both levels. AP level requires two endorsements in and of itself (158 5‐12 American History, 186 5‐12 All Social Sciences). On the list I found, there was no one 'full US history' course, it is instead broken down into Early and Modern US history... but it makes no sense. The requirements for both early and modern US history are 158 5‐12 American History, and 186 5‐12 All Social Sciences. Meaning, I take both classes, and I'm qualified to teach both an AP level and regular level AP class....weird. You would think with teaching an AP class, you would need to have a deeper understanding of the topic than just what is required for a regular level course.

All in all, I really don't understand these endorsement things, I'm not quite sure if they're classes I have to take, but I'm assuming so. Sooooo...if I sound like a complete fool, that's why. It's something I'm planning on looking into deeper before I start college.