is the dutch u/uw similar to the german Sie/Ihr?
In German you use i.e. Sie as the formal you(du) you'd say to your teaher "sie sind..." is the dutch u similar?
I have recently asked my tandem partner about it, and she meant, that though it might be in fact the same, but the Dutchies would be much less formal as the Germans, and there could be some situations where a Dutchman would say jij to you while a German would still use "Sie".
That's 100% correct. The Germans are a lot more formal than the Dutchies, as are the Belgians (sometimes even parents will address their kids as 'u'). A Dutchie would only use 'u' in a formal situatuon when they're talking to someone they don't know, and even then they might slip in a 'je' instead