Ключевые слова: advertising, background, billboard, black, blackboard, blank, board, business, chalk, chalk sticks, chalkboard, chalks, class, classroom, college, color, colorful, colorful backgrounds, colors, communication, concept, copy, copy space, drawing, education, empty, empty space, frame, green, grunge, knowledge, learn, lesson, message, nobody, old, room for text, school, school background, school supplies, space, student, study, teacher, text, texture, university, v, white, wooden,