This IB DP Theory of Knowledge (TOK) lesson introduces students to the idea of justified true belief (JTB) and examines why it may not be enough to explain what knowledge is. Students begin with simple scenarios and then work through the three JTB conditions: truth, belief, and justification. The lesson then moves into the Gettier problem, showing how a belief can be true and justified but still not count as knowledge. The resource is designed as a 60-minute TOK lesson and includes a full teache