Definition of "blackboard"
A large flat surface, finished with black slate or a similar material, that can be written upon with chalk and subsequently erased; a chalkboard.
Quotations
Drawings and pictures are more than mere ornaments in scientific discourse. Blackboard sketches, geological maps, diagrams of molecular structure, astronomical photographs, MRI images, the many varieties of statistical charts and graphs: These pictorial devices are indispensable tools for presenting evidence, for explaining a theory, for telling a story.
2012 March, Brian Hayes, “Pixels or Perish”, in American Scientist, volume 100, number 2, archived from the original on 19 February 2013, page 106
verb
third-person singular simple present blackboards, present participle blackboarding, simple past and past participle blackboarded