The problem is that, if a cog is going clockwise, any other cog it is meshed with will have to spin counterclockwise. The teeth lock together, so, if the “teachers” cog is going clockwise, the teeth on the right will push the left side of the “students” cog down, turning it counterclockwise. The problem is that the teeth of the “parents” cog links to both of the other cogs, grinding the whole thing, as well as parent-teacher interview night, to a halt.
