I'm Canadian, so I have no idea how blind people are educated in Germany. However, as a child, I remember being taught angles, clock faces, and compass directions. The method I was taught for angles was to place both my feet together, then turn my right foot, keeping my heels together, to some particular angle, say 90 degrees. Once I had turned my right foot at a 90 degree angle from my left foot, I could then turn my left foot to match. If I stepped out straight, I'd now be walking at a nearly exact 90 degree angle from the direction I was previously going. As an adult, I have never, ever, had any reason to do this. Also, this is not a technique anyone would use when we're following another person. It's only useful when following directions. When someone is guiding me, I'm supposed to get all of the information from there arm. If I'm following you properly, I should be a step behind you, so when you turn, I will just naturally follow. Also, if you step up or down, I should feel it from your arm position changing. In practice, some blind people are quick walkers, and will actually wind up a step ahead of their sighted guide. Others, like me, will get totally absorbed in an interesting conversation with the person guiding us, and just completely fail to pay attention. So the long and short of it is that everyone is slightly different. I usually get distracted and miss my guide stepping up or down, and perhaps their are some people who would prefer to be told about turns. If you offer help, most blind people will be perfectly fine letting you know how you can best help them.

It honestly depends on the blind person. I have a really good sense of direction, but if your leading a blind person, you usually don't need to tell them when they are turning because they will just use their cane and follow your direction automatically.