la grève des trousses

Following the example of their teachers, some of my 5e students also decided to go on grève.  They told me it was the "grève des trousses" and that they would not use their trousses that day.  A trousse is a pencil case that is super important to French students.  In it they have their assorted pen colors, ink refills for their plume pens, a compass, erasers, and most importantly, a ruler.  Yes, a ruler is very important.  Why, you might ask?  Well, because no French student would ever dare make a line that wasn't straight.  In any case, although the students on this particular day thought they would be pulling one over on me, I got the last laugh when they begrudgingly got out their pens and rulers to copy down their notes.  Heaven forbid they draw a line that wasn't straight...They just couldn't help themselves.    Grève fail.