The document summarizes a study that investigated the impact of Content and Language Integrated Learning (CLIL) on the English skills of 40 Thai high school students. The students' listening, reading, speaking, and writing skills were tested before and after three English lessons using CLIL. The results showed significant improvements in all four skills after using CLIL. CLIL helped students learn content and language simultaneously. The study concluded that CLIL is an effective technique for improving English skills in high school students.