Ключевые слова: adult, attending, background, blackboard, boy, caucasian, chalkboard, child, class, classroom, coaching, conference, corporate, education, explaining, female, girl, group, happy, indoors, learning, lecture, lesson, listening, meeting, men, modern, people, person, physics, presentation, professional, professor, room, school, seminar, sitting, students, study, studying, teacher, teaching, teaching school, teenage, training, tutor, university, woman, write, young,