Translation of mediana

I learned Russian during 8 years in highschool, but since I left school 6 years ago, I have forgotten most of it and did not have opportunity to speak or practice in any way. That's why I am on Vocabulix.
Yes, my Spanish is much better than your German, but it is not true that I do not want to learn with you. I think this is not an issue. Where do you come from in the U.S.? East or West coast?
First, let me thank you for your answer. And how can I support you further? I'd be very happy about it if we could both help in each other in learning Spanish. 'Tandem' learning beats all other methods.