Germany turned a local conflict between Austria-Hungary and Russia into a world war. Isn't Germany the responsible party here? I know this is an opinion but teachers told me that I make a good point. Does anyone agree with this? Why/ why not?
The question is controversial, in the sense that different modern historians express different opinions. Most maintain that several parties are responsible to some extent. As there is no objective criterion for the "share of responsibility" probably this question will be never settled. One also has to take into account that most modern histories of WWI are written by English-speaking historians. (I will be grateful if someone points to me a serious comprehensive history of WWI written by a modern German historian). On my own opinion, Russia's and Austria's part is at least as large as the German one.
"Germany turned a local conflict between Austria-Hungary and Russia into a world war". This is certainly wrong. Germany had an obligation to defend Austria in the case of a Russian attack, and Austria counted on this when it attacked Serbia. Similarly, Russia felt obliged to defend Serbia, and France had an obligation to help Russia. So from the very beginning, all understood that this is not a "local conflict". So one can say that "Russia turned a local conflict (between Austria and Serbia) into a world war. But of course this also would be an oversimplification.
As a serious research of the Russian role I can recommend S. McMeekin, Russian origins of the first world war, Cambridge 2011.