Ask Engineering Interview Candidates to Explain Something

Is this a new concept? Aside from interviews at Google which were 100% whiteboarding, I’ve always talked through a technical project or bug in interviews.

As an interviewer I always open with some form of this to loosen the candidate up, assess the validity of their resume, and sometime soon just to satisfy my own curiosity (tell me why you did x in z, compare framework a to b, how do you like working in z?).