Ключевые слова: academic, adult, boy, casual, caucasian, chair, chalk, child, children, class, classmate, classroom, education, elementary, explaining, formal, formula, geometry, greenboard, holding, kid, knowledge, learning, lesson, little, male, man, math, mathematics, mature, men, occupation, people, primary, pupil, rear, room, school, schoolboy, schoolchildren, sitting, student, study, studying, teacher, teaching, young,