Theory of Knowledge (TOK) explores how knowledge is gained, the validity of knowledge claims, and different areas of knowledge. TOK lessons involve open-ended questions, critical thinking, and reflection. The goal is not to answer questions definitively, but to think about knowledge. Key concepts include justification of knowledge using different ways of knowing, the relationship between truth and belief, and examining knowledge issues and claims within disciplines like the natural sciences, human sciences, history, ethics, religion, indigenous knowledge, and the arts.