A screen reader program will be the blind student's primary interface for replacing information contained on the screen. The screen reader program doesn't process the image of the screen like an Optical Character Recognition program would. Instead, it gathers information from the operating system (Windows, OSX, or Linux), and uses this information to speak the text. If a program doesn't communicate the proper information to the operating system, the screen reader will not be able to speak its text, even though the interface to that program appears to be textual. For that reason, it's impossible to tell whether a particular program is screen reader compatible merely by looking at it. Instead, each program must be separately tested with the screen reader enabled. Also note that two programs that present substantially the same interface may have different levels of accessibility. For example, on Linux, xterm terminal windows are not compatible with the Orca screen reader while GNOME terminals are compatible, even though the visual difference between the two is minimal.
It is important to note that many screen reader programs offer similar functionality, but are quite different in terms of interface, and browsing modes. This will cause confusion for a student if, for example, you give them instructions on completing a lab using NVDA but the student is using JAWS, or vice versa. It is generally safe to assume that a student will be trained in the use of their own screen reader program before beginning your class, or that Disability Services will work with that student to help them to get the proper training. Therefore, you should be able to avoid including screen-reader specific instructions in most cases.
There are several screen readers available on all of the major platforms. Some of the most common include Narrator, JAWS, NVDA, Orca, Speakup and VoiceOver.
Microsoft Narrator comes bundled with Microsoft Windows. It is compatible with Windows itself and some of the more basic applications for Windows, but is not considered a "full featured" screen reader, and will probably not be powerful enough for a blind student to successfully complete a programming lab.
JAWS (Job Access With Speech) is one of the most powerful and popular screen readers for the Windows platform. However, it is commercial software and is quite expensive (so you might not want to buy a copy just to test your applications with it). However, many of your blind students may already have access to JAWS before they sign up for your class. It is very powerful and supports different modes for browsing through the text in a document. It can allow the student to browse a document section-by-section, if that document has been structured using the proper document headers. It is frequently updated, and has application specific plug-ins that give it a high level of compatibility with many programs. There is a detailed tutorial available.
NVDA (NonVisual Desktop Access) is a free, open source alternative to JAWS for the Windows platform. It is full featured, but may not be updated as frequently as JAWS. There are several guides and tutorials available. It is a good choice for an instructor who wants to check accessibility for their applications and development environment, but doesn't have access to JAWS.
Most of the test results described in the page on screen reader compatibility are based on tests conducted with NVDA.
Orca is a free, extensible screen reader program for Linux. It was originally developed at Sun Computers, before moving fully into the open source community. It is integrated into the GNOME desktop environment, and comes bundled with several Linux distributions, including Fedora and Ubuntu. It is possible to install Ubuntu Linux using Orca without using the screen or mouse. Full documentation on using Orca is available. There were a number of tutorials available at one point, but most of those links are broken now (one downside of using open source software). As with the rest of the screen reader programs described here, some applications are compatible with Orca and some aren't. If you are trying to use an application in your class that isn't compatible with Orca, it might work with Speakup instead.
Speakup is another free, Linux-based screen reader program. It is probably not as well supported as Orca, but may work for some applications that are not compatible with Orca. Speakup works particularly well with "console based" applications such as the Lynx web browser and the Pine mail reader. The interface is quite different from Orca's interface, so a blind student may have to switch back and forth between screen reader programs if you require Speakup in your labs. This is "do-able," but is definitely more difficult for the student than using one screen reader program. A guide for using Speakup is available in unstructured text format. There are also tutorials available.
VoiceOver is built-in, advanced screen-reading technology integrated into the Mac OS X operating system. VoiceOver enables users with visual disabilities to control their computer using a rich set of keyboard commands and gestures. To turn on VoiceOver, press Command-F5 on your mac. Here is a link to the VoiceOver Info Guide. VoiceOver provides many ways to read text. You can read text a word, line, sentence, or paragraph at a time. You can hear words and characters spelled phonetically. You can also read text using VoiceOver gestures. AFB AccessWorld Magazine says, "Text Edit is the simple word processor that comes on all the macs. This is the application in which VoiceOver performed best. It is possible to write and edit documents, cut and paste text, and save documents as files in rich text format. This editor does not include a spell checker or other advanced word-processing functions."