I believe that the intended message of the poster below was something along the lines of “students are the most important part of education, and both teachers and parents need to work together with them”:
Click the photo to see the terrible engineering at full size.
However, if you know how gears work, you’ve already seen the problem with this diagram:
Simply put, the “Teachers” and “Parents” gears are trying to turn the “Students” gear in opposite directions simultaneously, and the entire system is stuck, useless and motionless. Come to think of it, this may have been the message the artist was trying to convey.