SPEAKER: CS50 starts in Scratch, of course, to give students a taste of what you can do with programming, especially without the distraction of syntax like parentheses and semicolons, and the like. But we then focus quite a few weeks on C, an older, more traditional text-based language that really gives students a sense of how computers and how programs work from the bottom up. 

But it's a language in which it's very time consuming, if not difficult, to solve certain problems. And so we eventually introduce languages like Python, which are higher level, so to speak, that make it much easier to solve certain problems, but they take for granted that you do hopefully understand what's going on underneath the hood.