Ключевые слова: academic, adult, asian, back, beautiful, blackboard, chalk, chalkboard, child, chinese, class, classroom, closeup, concept, drawing, education, elementary, equation, female, formula, girl, hand, holding, kids, knowledge, learn, literature, little, math, mathematical, mathematics, person, presentation, primary, problem, rear, school, smart, solving, student, study, studying, success, view, writing,