In the last five minutes of lecture, I asked people why they thought that cassette tapes so quickly replaced reel-to-reel technology in the last 1960's. People had many answers. I argued that cassettes won because they took an inconvenient collection of stuff (tape, reels, etc) and turned it into an "it", a "thing", an "object". Several students gave this answer as well talking about cassettes as "more convenient", "self contained", "encapsulated". I said that this is a good analogy for understanding what Java classes get us. A Java class is a way of packaging a set of variables along with some code into a self-contained, encapsulated, convenient object. I said we would pick up from there in Friday's lecture.