Ключевые слова: blackboard, book, business, caucasian, caucasian female, chalkboard, class, classroom, college, concept, cropped, education, elementary, female, formula, hand, kid, knowledge, learn, learning, lecture, lesson, math, mathematics, mid adult, mixedrace, occupation, one person, people, person, pupil, school, student, study, studying, teacher, teaching, unaltered, university, whiteboard, woman, writing,