Learning is more complex than memorization of facts. Students must learn to apply what they have learned to real life situtations. After all, very few jobs depend on recalling memorized facts.
Most jobs depend on application of knowledge or problem solving skills to solve complex problems.
Problem based learning attempts to engage students' curiosity and prepares students to think critically and analytically, and to find and use appropriate learning resources. In PBL, the content is introduced in the form of a problem to be solved. Students do not receive a lecture in advance. Instead, they receive the problem first, and then themselves find the information needed to solve the problem. This contrasts with traditional teaching where students hear a lecture, and are then tested on the contents of the lecture or application of the lecture contents.