Ключевые слова: 20s, black, blackboard, boy, casual clothing, caucasian, chalk, chalkboard, cheerful, child, classroom, education, female, green, happiness, happy, helping, holding, knowledge, learning, lesson, looking at camera, male, mathematics, number, portrait, school, schoolboy, schooling, showing, smiling, standing, student, studying, teacher, teaching, woman, writing, young adult,