Ключевые слова: adult, blackboard, book, caucasian, chalkboard, class, classmate, classroom, college, education, elementary, expertise, explain, explaining, group, high school, horizontal, indoor, intelligence, knowledge, learn, learning, lecture, lesson, male, man, mathematic, mature, old, person, problem, profession, professor, pupil, school, science, seminar, senior, standing, student, study, studying, teach, teacher, teaching, tutor, two people, university, whiteboard, woman,