What students take from our classes

Just reading a piece of science on the web (background microwave radiation) and then happened to glance at the comments section and was struck at how random the comments often appear to be. Leaving out the obvious spam ("Hi, I have a large collection of meteorites I'd like to sell") there are those who debate the implications of the finding (fine!) and then there are those who just go off on wild tangents -- "well, that proves there is/isn't a god", that "it explains why it rains so much", or "is the Earth conscious"?

And it occurred to me that the comment section of online columns, news reports etc., give me a bit of insight into what my students are actually thinking as I lecture -- that what I think I'm talking about and what is actually going through their brains at any given moment are probably largely unrelated. That while I'm lecturing, what they are taking in as initial input is then filtered through a kind of free association with the stuff already in there, and what they consequently take away from my lectures probably has very little overlap with the objectives listed on my lesson plan. Given what I see on their exam answers, I've always known that what I said and what they recall may not correspond all that well, but I've never really been able to open their heads and see the squirrel's nest of random associations that leads them from what I said to what they got. Unmoderated comment sections give us a Kind of view inside what the average citizen is thinking...well, I use the term 'thinking' somewhat loosely.

One thing that might help: actually telling our students what the lesson objective is for today. A lot of teachers seem to feel this should be "teacher-only" secret information. Which is bizarre. As my mentor used to regularly say to me, students can hit any target they're shown and that holds still for them. If their is a point to today's class, probably best to tell them that at the outset, but certainly by the conclusion of the class.