1 definition by Gemini Professor
Expression referring to an instructor's frustration (literally: mechanical pencil lead breaking under excessive comment writing pressure) while marking a student paper which violates both instruction and Standard American English.
After having marked 42 essays that compared and contrasted two poems, nearly every one of them ignoring the pointed lesson of the previous class, by the 43rd I was breaking lead when the student wrote that the poets had "concocted imagery" and employed "religious illusions".
by Gemini Professor February 22, 2011