Ключевые слова: advertising, background, billboard, black, blackboard, blank, board, chalk, chalkboard, class, classroom, college, communication, concept, copy, dirty, drawing, education, empty, frame, green, grunge, isolated, knowledge, learn, learning, lecture, lesson, message, note, old, primary, remember, reminder, school, scratch, space, study, symbol, teach, teacher, text, texture, textured, university, used, white, wood, wooden, write,