Ключевые слова: abc, aids, alphabet, back to school, background, blackboard, board, chalk, chalkboard, chart, childhood, class, classroom, college, condom, contraception, contraceptive, education, elementary, grade, homework, illustration, information, inscription, language, learn, learning, lecture, lesson, manual, material, math, notes, numbers, period, primary, quiz, reading, research, school, sex, sex education, student, study, studying, symbol, teacher, teaching, work, writing, youth,