This is a buret.  It is used to titrate chemicals.  It gives you great precision in the amount of chemicals added.  the part that controls the flow of chemicals is the "stopcock"  (stop that, its because you "cock" it to control or stop the flow).  The part that the chemical comes out of is the "nipple."  (Siiigh, gotta love teaching teenagers)

Sometimes the stopcock will stick.  There are a few tricks to loosen it, soaking it in warm water or soda.  There is something that will help prevent this from happening.

So the bookkeeper is gonna love my purchase order of "stopcock grease."