Ключевые слова: 2021, alternative, b, background, change, closed, concept, corona, corona virus, covid 19th, covid19, cube, decision, dice, disease, education, epidemic, green, hot spots, idea, incidence value, isolated, learn, lockdown, lower saxony, message, plan, plan b, politics, preparation, presence, rules, safety, scenario a, scenario b, school, strategy, symbol, text, turn, virus, word,