Software Tools for teaching XML
For the price (previously free, but now $35), Chami.com's HTML-Kit makes an excellent text editor for working with XML. It is a 2.8 MB download from the Web, runs under Windows, and requires the Java run time environment. I use build 292 Beta which is free, fairly stable, and contains useful features missing from build 290.
There are a number of plug-ins available for HTML-Kit that make working with XML code easier: XML Validator makes it easy to check your XML code for well-formedness and validity based on a DTD, TMXSLT provides a toolbar of tags to help with the creation of XSLT files, and ergXSLT allows you to test your transformations on XML with an XSLT file.
XMLSPY is an Integrated Development Environment for designing and editing applications involving XML, XML Schema, XSL/XSLT, and other XML-based technologies. The latest version is 5.0. The price ranges from $99 up. The home edition is a 16MB download for 30-day trial. It is a very nice development environment but it is not free.
Microsoft makes available as a free download XML Core Services (MSXML 4.0). You will need this in addition to MSXML 3.0, which installs with current versions of Windows, to provide support for the XML Schema language, a faster parser, and XSLT transformations in the browser.
Scalable Vector Graphics (SVG) is a way to describe vector graphics data for use over the Web. Vector graphics describe graphics in terms of lines, curves, etc. instead of bitmaps. A SVG viewer plug-in is available for free as a download.
For cutting edge XML technologies, the World Wide Consortium makes available the free Amaya editor/browser. It provides good support for MathML and partial support for SVG graphics.