Ключевые слова: academy, background, black, blackboard, calculus, chalk, chalkboard, child, children, classroom, college, different, educate, education, elementary, formulas, handwriting, idea, intelligence, kid, knowledge, learn, learning, lecture, lesson, lifestyle, math, mathematical, mathematics, middle, nobody, object, physical, physics, primary, school, science, sign, student, teacher, teaching, training, university, wall, write, written,