I Made up Technology, How Come You Guys Made It All?

Li Wu traveled through the post-apocalyptic wasteland and became a newly appointed teacher. In order not to go hungry every day, Li Wu, who did not know any knowledge, decided to talk about the happy days in his previous life every day and fool the students. Unexpectedly, they actually made various technologies from previous lives! A hundred years later, Li Wu's statue stood on top of the world. Li Wu stared at the world that was almost the same as his previous life. I made up all the knowledge, how can you make all the technology?