Pondering variables and direct instruction

The Communications Web site, http://cacm.acm.org, features more than a dozen bloggers in the [email protected] community. In each issue of Communications, we'll publish selected posts or excerpts.twitterFollow us on Twitter at http://twitter.com/blogCACMhttp://cacm.acm.org/blogs/blog-cacmRobin K. Hill considers the nature of variables, while Mark Guzdial reflects on renewed interest in the "direct instruction model."