In terms of the lecture content, it is 5 stars, but I deducted one star for the following reasons: - The mouse click sound is too loud, so sometimes I lose focus on the lecture. - When explaining with pictures, the mouse position is not visible, but there is a tendency to often use the demonstrative pronoun 'this', so it is sometimes difficult to understand. If only the two things above were improved, I think it would be an even better lecture.