Ключевые слова: advice, adviceboard, alert, awareness, blackboard, board, caution, cautionary, chalk, chalkboard, classroom, communication, concept, concern, danger, dangeralert, education, emergency, guidance, handwriting, information, instruction, instructionboard, knowledge, message, notice, precautionary, preparation, prevention, protection, public, red, reminder, risk, rules, safety, school, security, sign, signage, strategy, symbol, teaching, text, tip, visual, warning, written, writtenmessage,