The students don't know what they are missing. Were you aware that the few minutes at the start of class are the period where students have the best potential for paying attention? It is the place where ideally you should put the most important stuff that you want remembered. Not doing that is a wasted opportunity.
As for your lament that the time is wasted in review, review is actually one of the most important activities in the classroom. If you want long-term retention it is absolutely critical. Of course it is easy to not see the value of doing it.
As for my experience and part of why my attitudes changed, see http://bentilly.blogspot.com/2009/09/teaching-linear-algebra... for some of my teaching experience, and how I addressed these issues there. My attitudes only changed because I saw first hand how important that time was for learning.
Not that I blame you. When I only had only the amount of educational experience that you do, and like you only from one side of the educational equation, I too did not see how important these things really were. If you are like I was, then you won't understand unless, like me, you wind up experiencing the other side as well and thinking hard.
But even though you haven't experienced it, please pause in your certainty about the world long enough to accept that it is at least possible that, just perhaps, more experience would cause you to change your mind. Just as it changed mine.
> the few minutes at the start of class are the period where students have the best potential for paying attention
Oh, bull. Most are groggy, not thinking about the subject, and far from at their best. If you're an interesting teacher, their attention level goes up with time, not down. Learning in general exhibits a bell-curve-ish shape, not 1/x. Those first few minutes are best spent getting people back into the swing of what they're going to be learning about, starting the rise up that bell.
> time is wasted in review
Not saying it's a waste. Just that it's nothing that can't be picked up later by paying attention in class. That's kind of the nature of reviewing information - it's been covered before. Yes, the beginning is an ideal time to review, but that doesn't mean that it's impossible to make up, and by missing you simply can't learn anything that class period (which turning them away does mean). And remember, especially with a berating teacher, the ones that arrive late are the ones who want to learn. If they didn't, it's far simpler to just avoid the class. And interested students effectively come pre-primed for learning.
To sum up, my main point in all this: yes, arriving on time is important. But taking time to berate the student is the interruption, and is easily the least efficient way of dealing with the issue, and the most likely to alienate the student on both the subject and the teacher.
How, precisely, is this productive? It's just cutting them down when the teacher is feeling vindictive. If the teacher isn't aware of this, then they should really start looking at their motivations, because this is how it comes across. Unless they're a "repeat offender", in which case the class is probably on the teacher's side. It's simply downright mean, which is childish, which does nothing to further learning or respect for the teacher.
edit: I read your article, and it sounds like the sort of class I'd like. Most classes fail miserably at retaining info from the beginning, and the three-thirds setup sounds like a really good fit. The homework policy also appeals to me, as on-time is on-time, and very importantly it allows flexibility if needed. As a heads-up however, though frequent Q and A works with some professors, and when it does work it definitely keeps the class more alert, it's definitely not a one-size-fits-all solution. One of my gen-ed professors would be a perfect failing example of this; he'd end up waiting 10+ minutes for someone to answer his simple question, because everyone was sick of it. But he was hardly an engaging teacher.
As for your lament that the time is wasted in review, review is actually one of the most important activities in the classroom. If you want long-term retention it is absolutely critical. Of course it is easy to not see the value of doing it.
As for my experience and part of why my attitudes changed, see http://bentilly.blogspot.com/2009/09/teaching-linear-algebra... for some of my teaching experience, and how I addressed these issues there. My attitudes only changed because I saw first hand how important that time was for learning.
Not that I blame you. When I only had only the amount of educational experience that you do, and like you only from one side of the educational equation, I too did not see how important these things really were. If you are like I was, then you won't understand unless, like me, you wind up experiencing the other side as well and thinking hard.
But even though you haven't experienced it, please pause in your certainty about the world long enough to accept that it is at least possible that, just perhaps, more experience would cause you to change your mind. Just as it changed mine.