Ключевые слова: background, black, blackboard, blank, board, caucasian hand, chalk, chalkboard, cheerful, classroom, college, conceptions, copy book, drawings, education, educational, female, fingers, hands finger, holding, knowledge, learn, learning, lecture, lesson, looking, man professor, modern, occupation, people, person, plans, school class, science, scientific, show process, showing, shows, space, standing, student, study, teach, teacher, teaching, theories, university, white, woman, write formulas,