Popper's theory of learning is sometimes met with incredulity because Popper claims that there is no transference of knowledge or knowledge elements from outside the individual, neither from the physical environment nor from others. Instead, he claims that we can improve our present theories by discovering their inadequacies. The intent of this article is not to persuade educators to adopt Popper's approach uncritically to build their professional knowledge. Rather, it presents a discussion on the need for teachers to adopt a critical approach in eliminating what is inadequate and preserve what is adequate by modifying or abandoning whatever traditions or practices that are inadequate to improve their teaching practice. Popper claims that knowledge advances by searching for and eliminating error contained in our theory. In other words, we can improve our present theories by finding out their inadequacies.