Interactivity in Web-based Courses

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Client-side versus Server Side.

The conditional link in the demo course was written in Perl. When you click on the link, the server looks in a database to see if you have completed the appropriate quiz. It then returns different URL's dependent on the answer. Similarly, when you take a quiz with a course management system, the data is sent back and forth to the server and the computation is done there. This is called server side interactivity.

A cute example of server-side interactivity - which is neither server-side nor interactive - is the magic trick the mysterious rabbit. Definitely worth trying!

The most common types of interactivity in Web courses are client side. These have the advantage of not bogging down the server and (usually) exhibiting a more uniform and often quicker response time. If they are written in Javascript, they don't even need a server. Java applets are downloaded from the remote site, but they run on the client machine. VBscript and ActiveX are Microsoft options about which I plead ignorance.

By way of explanation, Javascript is a language which allows you to access, control, and alter the elements of a Web page, such as forms, images, the location of the URL displayed, "cookies",and text. Javascript includes the ability to do computations and parse strings. Java is a full-blown object-oriented programming language which can run its own GUI inside of an applet box. It is far more powerful and general but also harder to use for the casual programmer. The best general source of Javascript scripts and Java applets is http://www.gamelan.com.

An interesting mix of interactivity is provided by hybrid HTML-server/CD-ROM solutions. Archipelago software and Academic Systems are two companies exploring this approach.

Virtual Reality.

At the high end of the interactivity spectrum is virtual reality and its associated scripting language VRML (virtual reality markup language). VRML allows you to display 3-D graphical "worlds", such as the graph of a function of two variables or a model of a molecule, and walk around in the world. It is hard to think of a more powerful visualization technique, but in my experience VRML can be unstable and there isn't much good stuff around in the educational area of my discipline.

VRML requires a browser plugin to display. We have found that anytime you require a plugin, you will get calls from students about installation, so you need to be prepared to either dispense tech support to quickly hand the student off to someone who does.

This brings up the issue of other plugin solutions. The most highly developed is Macromedia's Shockwave which allows you to run Director movies via the Web. Examples and sources include The Macromedia Shockzone and the very well-done 6 Billion Human Beings Served. You need the free plugin to run these.

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