Ключевые слова: alert, amplification, announcement, attention, background, black, blackboard, broadcast, chalk, chalkboard, classroom, communication, concept, contrast, device, drawing, education, equipment, hand, handheld, idea, influence, information, instruction, knowledge, learning, lecture, media, megaphone, message, minimalism, noise, object, power, presentation, school, simplicity, sound, speaker, speech, student, symbol, talk, teacher, teaching, texture, tool, voice, white, writing,