Ключевые слова: advertising, announcement, antique, background, billboard, black, blackboard, blank, board, business, chalk, chalkboard, class, classroom, color, copy, drawing, dust, educate, education, empty, frame, green, horizontal, isolated, learn, lesson, message, old, pattern, presentation, retro, school, smudge, space, studying, teach, texture, textured, vintage, wood, wooden, work, write,