Ключевые слова: abstract, advancement, banner, blackboard, board, bulb, business, chalk, chalk board, chalkboard, class, classroom, college, concept, design, dirty, drawing, education, frame, graduate, grunge, hat, icon, idea, knowledge, lamp, learn, lesson, lightbulb, message, mortarboard, motivation, note, old, promotion, school, sign, solution, studying, success, symbol, teaching, university, used,