Boise Ed sends this in: “I think they are holding paper clips. What that has to do with the speech line is anyone’s guess.”
As I remember what a grade school classroom can do with paper clips if someone finds some rubber bands, I think I’d take my chances with rulers.
Comics I Don't Understand 
The teacher is showing that standard measures are arbitrary, so as long as we all agree to do so we can measure things in paper clips as well as with inches/cms. This has the added advantage of not requiring rulers which can be used for sword fights.