Ключевые слова: advertising, announcement, background, billboard, black, blackboard, blank, board, business, chalk, chalkboard, class, classroom, clean, close, communication, concept, copy, copyspace, design, drawing, education, empty, eraser, frame, green, information, isolated, learn, learning, message, note, notice, object, old, pattern, primary, school, space, square, study, teach, template, text, texture, white, wood, wooden, write,