Ключевые слова: bench, boys, caucasian, childhood, children, class, classroom, communication, education, elementary, equation, explaining, female, friends, girl, group, indoor, knowledge, learn, learning, lecture, lesson, man, mathematics, midadult, people, portrait, problem, pupil, school, schoolboy, schoolkid, smile, social, solution, solving, standing, study, studying, teacher, teaching, times, together, university, university student, whiteboard,