Wednesday, January 30, 2013


For a while now, I've been trying not to print out copies of papers I'm using for class. I had a Kindle DX a while back, and I tried loading PDFs of papers into it. But the page rendering was so slow it was painful, and a real problem in class itself, since finding a particular passage would simply take too long.
More recently, I've acquired a Samsung Galaxy Tab 10.1, which makes for an excellent e-reader. It has a nice, bright screen, good resolution (1280x800), and lots of memory. Plus, I can access my course web site, or JSTOR, or whatever, directly from it (and with tools like AndFTP, I can even access my servers using SFTP and public key authentication).
But as I've mentioned elsewhere, a lot of the material I've scanned for my own use is in DjVu format, so I recently found myself needing to find a DjVu reader for Android.
It turns out (unsurprisingly, really) that there are several options, but the one on which I've settled for now is EBookDroid, a free and open source (GPL'd) ereader. Not only does it handle DjVu, it's got a lot of other nice features, such as the ability to set lots of named bookmarks (making particular passages easy to find). But one of the nicest things about it is that it will automatically split pages, if the file you are reading happens to have facing pages on a single page, like a photocopy. And it will automatically scale pages to the content area, not to mention wash your laundry and make your dinner. An excellent tool.
I've seen some people mention that EBookDroid "hijacks" PDF links from the browser, but I have not seen this issue myself. It does register itself as one possible PDF reader, but that is all.

Scan Tailor

For quite some time now, I've been putting all the readings (except books) for my various classes online, on my course websites (such as here or here). In the good cases, this just means downloading stuff from JSTOR or some equivalent, or linking directly to it, though I very often convert the PDFs I get that way to DjVu files, since (a) the DjVu files are often a lot smaller (like one tenth the size), and (b) I prefer to have files where two pages appear on a single page, so that when they are printed you don't waste so much paper.
I've developed a number of tools to make this easier to do. I'll blog about them later. (Some of them are already available here.) What I wanted to mention today is a really, really cool program I found last weekend, called "Scan Tailor". It's "free and open source" (GPLv3) and available for Linux, OSX, and Windoze.
I've found that the easiest way to scan stuff I need from books (e.g., Dummett's "Frege's Myth of the Third Realm", from Frege and Other Philosophers) is first to make a photocopy of the paper and then to scan that. (This is easiest with a sheet-fed scanner, such as the HP Scanjet 5590, which works fine with Linux.) You can simply make a PDF or DjVu from the result, but, if you just do that, it will usually look like crap. For one thing, you get big black marks along the sides and, often, down the middle (where the spine of the book is). And the pages can be hard to read on screen, since they are often not quite square. Even half a degree's rotation is easy to see, and very annoying.
So, in the past, I'd load the pages one by one into Gimp (an open source image editor) and fix them up. But this was time consuming, and hard to get right. That is where Scan Tailor comes to the rescue.
Here's how it works. You put all the page images into some directory, and then you open Scan Tailor and create a new "project", pointing the program at that directory. All the pages then get loaded up. You can then rotate them, if need be. But the really useful bit is that the program will then automatically (i) split the pages in half (which you need to do for the next step), (ii) deskew them (i.e., correct for rotation of the text), (iii) put a bounding box around the actual text (thus eliminating the black marks), (iv) put clean new margins around that text, (v) despeckle the images (remove stray black dots), and then (iv) output the resulting page images to a directory of your choosing, so you can assemble them into a PDF or a DjVu.
And at every one of those steps, you can intervene to make manual corrections, if need be. It totally, totally rocks.

The Grand Teaching Experiment

Over the last couple years, I've become very dissatisfied with the way I've always taught my non-logic classes, e.g., classes on philosophy of language. These tend to be fairly small classes, with enrolment in the range of 10-15, and the basic model has been this: I've lectured on Mondays and Wednesdays, and we have had discussion on Fridays, led by me.
But I've read several things recently suggesting that lecturing is not a very effective way to get students to learn things. So this semester, in my course on Theories of Truth (Phil 1890D), I'm trying something different. I propose to blog about it from time to time.
The first thing I'm doing is trying to make use of Brown's new online teaching framework, called "Canvas". It does quite a lot. For example, there is an integrated conferencing system that I may try to use later. And it has simpler stuff, like the ability to schedule assignments, which are then automatically entered into a "grade book". But the main thing I'm using is the discussion board. For each of the readings, I've set up a discussion thread, and I'm requiring everyone in the class to post to it prior to class.
Obviously, this is just taking the place of the "response papers" that lots of people use, anyway, but it has a few advantages.
  1. It's easy for me to comment on people's responses simply by replying in the discussion thread. As a result, they can get feedback before we meet for class. 
  2. The students' responses, and my comments, are visible to the other students, so there is some opportunity for them to learn from each other. So far, there has only been a little discussion among the students, but I'm hopeful that, as we get into the semester, and as we all adjust to this new system, there will be more. (I've set it up so they have to post before they can see what other people wrote, for the obvious sort of reason.)
  3. Since contributing to discussion is an "assignment", it is linked to the grade book, and I can enter grades (not much more than "did" or "didn't") very easily.
Much of this, of course, could be done with a Google Group, but the way Canvas automatically generates a syllabus from my discussion assignments is very nice. And I can add the other course assignments, too, so a calendar for the semester is automatically created.
The second thing I'm doing differently is I'm not lecturing. At all. I told the students this at the first meeting, and when I walked into the first "real" class, I had no lecture notes. I'm trying to run the entire class as discussion.
The days that would previously have been devoted to lecture are now devoted to discussion that is aimed at understanding the readings. The day that was previously devoted to discussion is now devoted to discussion aimed at evaluating and criticising the readings. We've had two of the former so far (on Austin's and Strawson's famous papers on truth), and I'm not sure yet how they are going. My strategy has been to identify topics from the papers that we should talk about. So, in the case of Strawson's paper, for example, these were: His criticisms of Austin's account of (i) statements, (ii) facts, and (iii) correspondence, and (iv) his own positive account of the use of "true". The first class seemed to go pretty well. The second one, a bit less so, and I ended up talking more. But that may simply have been because Strawson's paper is quite hard, and maybe that is a sign that I should do something else.