Nobody knows everything about every subject. Nobody knows everything about even one subject. If somebody did know everything about a subject, there's a high probability that he/she can't remember it all or keep up with new and emerging changes. For graduate computer science courses, such as introduction to numerical methods and graph theory, the best way to learn is "cramming" from a borrowed textbook. Software quality analysts (QA) and testers tend to know, what they know and ask the question needs asking. And they work hard to gather knowledge about their field, where they have gaps. The field of computer software engineering truly requires lifelong learning. Getting to learn about new things is part of the fun. A jaunt into a new area can reenergize burned-out QA analysts or testers; QA managers should keep this in mind. Countless times, such questions at walk-throughs have required system designers or quality managers to explain concepts, algorithms, or processes in simple terms.