Ключевые слова: 20s, adult, answering, attention, caucasian, classroom, communication, concentrating, conversation, desks, education, elementary school, guidance, horizontal, incidental people, indoors, knowledge, learning, lesson, listening, man, medium group of people, mentoring, millennials, multiethnic group, one person, part of person, pointing, pupils, question, raising hands, school, schoolboys, schoolchildren, schoolgirls, selective focus, sitting, standing, students, talking, teacher, teaching, three quarter length, volunteering, waist up, whiteboard, young adult,