Ключевые слова: 20s, 30s, academic, adult, arms, background, beautiful, blackboard, casual, caucasian, chalkboard, cheerful, class, classroom, confident, copy space, crossed, education, educator, engagement, environment, equations, female, happy, instructor, job, knowledge, learning, lesson, math, one, outfit, portrait, professional, russian, school, schoolteacher, setting, smile, smiling, student, subject, successful, teacher, teaching, university, white, whiteboard, woman, young,