Ключевые слова: academic, background, billboard, black, blackboard, blank, board, brush, business, chalk, chalkboard, classroom, concept, copy, crayon, design, drawing, educate, education, empty, equipment, frame, glass, green, grunge, hand, horizontal, icon, isolated, label, learn, learning, nobody, red, school, schooling, schoolroom, sign, single, space, straight, symbol, teach, teacher, teaching, text, texture, water, white, write,