Ключевые слова: advertising, background, billboard, black, blackboard, blank, board, brush, business, chalk, chalkboard, class, classroom, clean, communication, concept, copy, drawing, dust, education, erase, eraser, erasing, frame, green, grunge, hand, hold, horizontal, isolated, learn, message, paper, room, rubber, school, sign, slate, space, sponge, study, teach, teacher, text, texture, university, vintage, white, wood, write,