Content and Language Integrated Learning (CLIL) is an approach where students learn new content in a foreign language at the same time. The theory is that focusing on meaningful content helps students understand and use the target language as a learning tool. CLIL differs from topic-based approaches in that the main objective is for students to learn new content while also learning the language. The document discusses the AICLE approach used in upper secondary schools, which complements communicative task-based learning in lower secondary schools by motivating students to solve problems and learn how to do things in other languages.