In the performance section of the piano board, we were discussing whether it's important for pianists to practice scales. This example here certainly bolsters the argument of the pro-scale crowd. However, just because you agree that knowledge of the scales is important doesn't mean you will necessarily think they need to be fingered the same, wherever they occur. A good fingering depends on the rhythmic and dynamic effect you want to achieve, as well as on the set of keys involved. Here, to practice this big bad double scale, Margherita, I would recommend you start at the ending. Put left hand finger 5 on middle C and right hand finger 1 on high C. Now, do the last 5 notes of the scale, forwards and backwards, faster and faster until your fingers are comfortable with those last 5 notes of the scale. Now, put left hand finger 4 on the F# below middle C, right hand finger 1 on F# below high C. Do the four notes of the scale, starting with the F#'s. Back and forth, faster and faster. Now combine them with the 5 notes in each hand done before. Do the 9 scale notes with each hand, back and forth, faster and faster. Any guesses as to where I'm taking this? The next step will be to put left hand finger 4 on the B-flat a ninth below middle C and the right hand finger 1 on the B-flat a ninth below high C. Add to the nine notes in each hand previously discussed. Then left hand finger 4 on E-flat above low C, right hand finger 1 on E-flat above middle C. Finally, left-hand finger 5 on G below low C, and right hand finger 1 on G below middle C. I know that at this point, disciples of Czerny are fit to be tied because I'm advising you to use the thumb on a black key and cross your right thumb under your right 5th finger. But all I can do is say what would work for me.