Ключевые слова: background, billboard, black, blackboard, blank, board, business, chalk, chalkboard, check, checklist, class, classroom, clipboard, communication, concept, copy, data, design, do, drawing, education, empty, form, grunge, illustration, information, letter, list, memo, message, note, number, object, office, plan, remind, school, shape, space, study, studying, teach, test, texture, white, work, write,