Ключевые слова: 4k, arithmetic, asian, blackboard, calculating, chalkboard, challenge, child, childhood, children, classroom, complexity, concentration, confusion, contemplation, curiosity, despair, difficult, education, elementary, expression, frustration, india, indian, kid, knowledge, learning, lesson, math, mathematics, number, preschool, problem, school, schoolboy, solution, solve, student, study, think, thoughtful, trouble, uncertainty,