For clarity, I have a young relative who will shortly be attending a CAP 413 R/T course as part of his sponsored PPL. The instructor has told him to swot-up before the course starts. A day visit to an ATC unit or just listening in to some R/T chat probably won't give him the depth of knowledge. I recall a new pilot telling me that he used an App to learn R/T and that it was great. Unfortunately, at the time I didn't have need to ask him which App he used. Has anybody got any suggestions?