no such thing like the waste of time. I think everything matters. even if you just stare into a nutcase there is something in that moment you can use some day. 
I told the students to take a look at their daily life and find something they might use plenty of time for and analyze that precious waster with drawing.
a bit like I did with my diploma four years earlier in the same school.

julia was so nice to print and bind a little A4-book with the results. here i show some of my favourites.