For some reason, they locate the assignment directory (folder) using a different pathname in some of the assignments. Another way to figure out the path it is to insert a new cell in the notebook (Insert → Cell Above) with this command:
!pwd
And then execute that. The exclamation point (!) as the first character in a Jupyter cell says that what follows is a linux shell command, not python. Here’s what you get in the U-Net Notebook:
/tf/W3A2
If you are using the “File → Open”, “New → Terminal” method to get a shell window, then you need to do:
cd /tf/W3A2
Here’s another thread that gives the "tar"and “split” command sequence that you need. You’ll have to adjust the pathnames depending on the assignment.