In February, COVID-19 hit Korea. Korea's new semester always begins in March. But then schools have to be closed and the period has been long. Instead, Korea unprecedentedly started school online. Korean teachers had to go online too suddenly. They had no preparation. Before COVID-19 emerged, the trend of education in Korea was group learning and cooperative teaching. Only a few leading teachers were using teaching methods based on online platforms as Digital Literacy education. I started using tablets and mobile phones two years ago and taught classes based on online platforms. At that time, most teachers were not interested, and some even showed skepticism about them. As such, online learning was only the beginning of school classes. However, with the sudden start of online education, Korean teachers suddenly had to change their teaching methods to one based on online platforms without any preparation and adjustment period. Teachers had to choose one of the three. They had to take a video of their class and upload it to an online learning place. Or They had to link online learning materials to students. The other was to do an online live lesson. All of this is more of a revolution than a change. This revolution was a challenge for young teachers who were somewhat familiar with digital. But above all, it was beyond a challenge and a great sense of fear and crisis for older teachers. Before COVID-19, they were respected teachers with rich educational background and know-how. Young teachers asked them for advice and help. However, everything changed at once. As online learning began, they not only had to learn an unfamiliar digital world, but they also had to ask for advice and help from young teachers, not their own. Their situation suddenly changed overnight.