The Fourth Lesson from Kevin (Kevin's Fourth Lesson)

Today, I had my fourth lesson from Kevin. Kevin is an American teacher. He taught us some common idioms used by Americans, such as Lost his marbles, brand-spanking new, couch potato, etc. Some of them are familiar to us, but some are not. I think idioms are very important for us, especially for spoken language. During the lesson, Kevin introduced an English programme called Good Mythical Morning. I found it very interesting, although I didn't understand it completely.

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I do not see any glaring errors in here. The only thing I would note is that "programme" is not standard in American English spelling. I believe it is standard in British English spelling.

Also, you begin by saying "I had my fourth lesson from Kevin." and then switch to "He taught us some common..." This is a switch from singular to plural. I am not sure how many he was teaching, but this would need some corrections depending on whether it was just you or multiple students.