The document summarizes four units of a course on writing skills in English. Unit 1 covers scientific articles and videos on writing. Unit 2 examines scientific articles and videos on punctuation frequency and usage. Unit 3 analyzes avoiding faulty sentences through a scientific article and video. Unit 4 discusses the role of commas in sentences through a summary, tips, scientific article, and how omitting or misplacing commas can lead to misinterpretations. A bibliography of additional resources is provided.